Pulsed illumination in a fluorescence imaging system

ABSTRACT

Pulsed fluorescence imaging in a light deficient environment is disclosed. A system includes an emitter for emitting pulses of electromagnetic radiation and an image sensor comprising a pixel array for sensing reflected electromagnetic radiation. The system includes a controller configured to synchronize timing of the emitter and the image sensor. The system is such that at least a portion of the pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation having a wavelength from about 770 nm to about 790 nm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/864,231, filed Jun. 20, 2019, titled “PULSEDILLUMINATION IN A HYPERSPECTRAL AND FLUORESCENCE IMAGING ENVIRONMENT,”which is incorporated herein by reference in its entirety, including butnot limited to those portions that specifically appear hereinafter, theincorporation by reference being made with the following exception: Inthe event that any portion of the above-referenced provisionalapplication is inconsistent with this application, this applicationsupersedes the above-referenced provisional application.

TECHNICAL FIELD

This disclosure is directed to digital imaging and is particularlydirected to fluorescence imaging in a light deficient environment.

BACKGROUND

Advances in technology have provided advances in imaging capabilitiesfor medical use. An endoscope may be used to look inside a body andexamine the interior of an organ or cavity of the body. Endoscopes areused for investigating a patient's symptoms, confirming a diagnosis, orproviding medical treatment. A medical endoscope may be used for viewinga variety of body systems and parts such as the gastrointestinal tract,the respiratory tract, the urinary tract, the abdominal cavity, and soforth. Endoscopes may further be used for surgical procedures such asplastic surgery procedures, procedures performed on joints or bones,procedures performed on the neurological system, procedures performedwithin the abdominal cavity, and so forth.

In some instances of endoscopic imaging, it may be beneficial ornecessary to view a space in color. A digital color image includes atleast three layers, or “color channels,” that cumulatively form an imagewith a range of hues. Each of the color channels measures the intensityand chrominance of light for a spectral band. Commonly, a digital colorimage includes a color channel for red, green, and blue spectral bandsof light (this may be referred to as a Red Green Blue or RGB image).Each of the red, green, and blue color channels include brightnessinformation for the red, green, or blue spectral band of light. Thebrightness information for the separate red, green, and blue layers arecombined to create the color image. Because a color image is made up ofseparate layers, a conventional digital camera image sensor includes acolor filter array that permits red, green, and blue visible lightwavelengths to hit selected pixel sensors. Each individual pixel sensorelement is made sensitive to red, green, or blue wavelengths and willonly return image data for that wavelength. The image data from thetotal array of pixel sensors is combined to generate the RGB image. Theat least three distinct types of pixel sensors consume significantphysical space such that the complete pixel array cannot fit in thesmall distal end of an endoscope.

Because a traditional image sensor cannot fit in the distal end of anendoscope, the image sensor is traditionally located in a handpiece unitof an endoscope that is held by an endoscope operator and is not placedwithin the body cavity. In such an endoscope, light is transmitted alongthe length of the endoscope from the handpiece unit to the distal end ofthe endoscope. This configuration has significant limitations.Endoscopes with this configuration are delicate and can be easilymisaligned or damaged when bumped or impacted during regular use. Thiscan significantly degrade the quality of the images and necessitate thatthe endoscope be frequently repaired or replaced.

The traditional endoscope with the image sensor placed in the handpieceunit is further limited to capturing only color images. However, in someimplementations, it may be desirable to capture images with fluorescenceimage data in addition to color image data. Fluorescence is the emissionof light by a substance that has absorbed light or other electromagneticradiation. Certain fluorescent materials “glow” or emit a distinct colorthat is visible to the human eye when the fluorescent material issubjected to ultraviolet light or other wavelengths of electromagneticradiation. Certain fluorescent materials will cease to glow nearlyimmediately when the radiation source stops.

Fluorescence occurs when an orbital electron of a molecule, atom, ornanostructure is excited by light or other electromagnetic radiation,and then relaxes to its ground state by emitting a photon from theexcited state. The specific frequencies of electromagnetic radiationthat excite the orbital electron, or are emitted by the photon duringrelaxation, are dependent on the atom, molecule, or nanostructure.Fluorescence imaging has numerous practical applications, includingmineralogy, gemology, medicine, spectroscopy for chemical sensors,detecting biological processes or signals, and others. Fluorescence canbe used in biochemistry and medicine as a non-destructive means fortracking or analyzing biological molecules. Some fluorescent reagents ordyes can be configured to attach to certain types of tissue and therebydraw attention to that type of tissue.

However, fluorescence imaging requires specialized emissions ofelectromagnetic radiation and specialized imaging sensors capable ofreading the specific relaxation wavelength for a specific fluorescentreagent. Different reagents or dyes are sensitive to differentwavelengths of electromagnetic radiation and emit different wavelengthsof electromagnetic radiation when fluoresced. A fluorescent imagingsystem may be highly specialized and tuned for a certain reagent or dye.Such imaging systems are useful for limited applications and are notcapable of fluorescing more than one reagent or structure during asingle imaging session. It is very costly to use multiple distinctimaging systems that are each configured for fluorescing a differentreagent. Additionally, it may be desirable to administer multiplefluorescent reagents in a single imaging session and view the multiplereagents in a single overlaid image.

In light of the foregoing, described herein are systems, methods, anddevices for fluorescent imaging in a light deficient environment. Suchsystems, methods, and devices may provide multiple datasets foridentifying critical structures in a body and providing precise andvaluable information about the body cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive implementations of the disclosure aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified. Advantages of the disclosure will becomebetter understood with regard to the following description andaccompanying drawings where:

FIG. 1 is a schematic view of a system for digital imaging in a lightdeficient environment with a paired emitter and pixel array;

FIG. 2 is a system for providing illumination to a light deficientenvironment for endoscopic imaging;

FIG. 2A is a schematic diagram of complementary system hardware;

FIGS. 3A to 3D are illustrations of the operational cycles of a sensorused to construct an exposure frame;

FIG. 4A is a graphical representation of the operation of an embodimentof an electromagnetic emitter;

FIG. 4B is a graphical representation of varying the duration andmagnitude of the emitted electromagnetic pulse to provide exposurecontrol;

FIG. 5 is a graphical representation of an embodiment of the disclosurecombining the operational cycles of a sensor, the electromagneticemitter, and the emitted electromagnetic pulses of FIGS. 3A-4B, whichdemonstrate the imaging system during operation;

FIG. 6A is a schematic diagram of a process for recording a video withfull spectrum light over a period of time from t(0) to t(1);

FIG. 6B is a schematic diagram of a process for recording a video bypulsing portioned spectrum light over a period of time from t(0) tot(1);

FIGS. 7A-7E illustrate schematic views of the processes over an intervalof time for recording a frame of video for both full spectrum light andpartitioned spectrum light;

FIG. 8 illustrates a pixel array of an image sensor comprising aplurality of pixels for sensing discrete exposure frames to generate aYCbCr image frame;

FIG. 9 illustrates a pixel array of an image sensor comprising aplurality of pixels for sensing discrete exposure frames to generate aYCbCr image frame;

FIG. 10 illustrates a pixel array of an image sensor comprising aplurality of pixels for sensing discrete exposure frames to generate aYCbCr image frame;

FIG. 11 illustrates a pixel array of an image sensor comprising aplurality of pixels for sensing discrete exposure frames to generate anRGB image frame;

FIG. 12 illustrates a pixel array of an image sensor comprising aplurality of pixels for sensing discrete exposure frames to generate aYCbCr image frame;

FIG. 13 illustrates a pixel array of an image sensor comprising aplurality of pixels for sensing discrete exposure frames to generate anRGB image frame;

FIG. 14 illustrates a pixel array of an image sensor comprising aplurality of pixels for sensing discrete exposure frames to generate aYCbCr image frame;

FIG. 15 is a schematic diagram of a process flow for applying correctionalgorithms and for applying frame reconstruction to a plurality ofexposure frames for generating a YCbCr image frame with fluorescencedata overlaid thereon;

FIG. 16 is a schematic diagram of a process flow for applying correctionalgorithms and frame reconstruction to a plurality of exposure framesfor generating an RGB image frame with fluorescence data overlaidthereon;

FIG. 17 is a schematic diagram of color fusion hardware;

FIG. 18 illustrates two corresponding histograms of black-correctedsignal for a region of an exposure frame captured with long exposurepixels and short exposure pixels;

FIG. 19A is a schematic diagram of an exposure frame pipeline for theY-Cb-Y-Cr pulsing pattern;

FIG. 19B is a schematic diagram of an exposure frame pipeline of a 120Hz frame capture rate for generating a video stream;

FIG. 20 is a schematic diagram of a pattern reconstruction process forgenerating an RGB image with fluorescence data overlaid thereon bypulsing partitioned spectrums of light;

FIGS. 21A-21C illustrate a light source having a plurality of emitters;

FIG. 22 illustrates a single optical fiber outputting via a diffuser atan output to illuminate a scene in a light deficient environment;

FIG. 23 illustrates a portion of the electromagnetic spectrum dividedinto a plurality of different sub-spectrums which may be emitted byemitters of a light source in accordance with the principles andteachings of the disclosure;

FIG. 24 is a schematic diagram illustrating a timing sequence foremission and readout for generating an image frame comprising aplurality of exposure frames resulting from differing partitions ofpulsed light;

FIG. 25 illustrates an imaging system including a single cut filter forfiltering wavelengths of electromagnetic radiation;

FIG. 26 illustrates an imaging system comprising a multiple cut filterfor filtering wavelengths of electromagnetic radiation;

FIGS. 27A and 27B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor having aplurality of pixel arrays for producing a three-dimensional image,wherein the plurality of pixel arrays and the image sensor are built ona plurality of substrates;

FIGS. 28A and 28B illustrate an implementation having a plurality ofpixel arrays for producing a three-dimensional image in accordance withthe principles and teachings of the disclosure;

FIGS. 29A and 29B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor built on aplurality of substrates, wherein a plurality of pixel columns formingthe pixel array are located on the first substrate and a plurality ofcircuit columns are located on a second substrate and showing anelectrical connection and communication between one column of pixels toits associated or corresponding column of circuitry.

DETAILED DESCRIPTION

Disclosed herein are systems, methods, and devices for digital imagingthat may be primarily suited to medical applications such as medicalendoscopic imaging. An embodiment of the disclosure is an endoscopicsystem for fluorescence and color imaging in a light deficientenvironment. Such methods, systems, and computer-based productsdisclosed herein provide imaging or diagnostic capabilities for use inmedical robotics applications, such as the use of robotics forperforming imaging procedures, surgical procedures, and the like.

Conventional endoscopes are designed such that the image sensor isplaced at a proximal end of the device within a handpiece unit. Thisconfiguration requires that incident light travel the length of theendoscope by way of precisely coupled optical elements. The preciseoptical elements can easily be misaligned during regular use, and thiscan lead to image distortion or image loss. Embodiments of thedisclosure place an image sensor within the highly space-constrainedenvironment in the distal end of the endoscope itself. This providesgreater optical simplicity when compared with implementations known inthe art. However, an acceptable solution to this approach is by no meanstrivial and introduces its own set of engineering challenges.

There can be a noticeable loss to image quality when the overall size ofan image sensor is minimized such that the image sensor can fit withinthe distal tip of an endoscope. The area of the pixel array of the imagesensor can be reduced by reducing the number of pixels and/or thesensing area of each individual pixel. Each of these modificationsimpacts the resolution, sensitivity, and dynamic range of the resultantimages. Traditional endoscopic imaging systems are geared toward sensingsteady broadband illumination and providing color information by virtueof segmented pixel arrays such as the Bayer pattern array. In light ofthe deficiencies associated with segmented pixel arrays, disclosedherein are alternative systems and methods that use a monochromatic (maybe referred to as “color agnostic”) pixel array that does not includeindividual pixel filters. In the embodiments disclosed herein, the colorinformation is provided by pulsing an emitter with different wavelengthsof electromagnetic radiation. The pulsed imaging system disclosed hereincan generate color images with fluorescence imaging data overlaidthereon.

In an embodiment, the color information is determined by capturingindependent exposure frames in response to pulses of differentwavelengths of electromagnetic radiation. The alternative pulses mayinclude red, green, and blue wavelengths for generating an RGB imageframe consisting of a red exposure frame, a green exposure frame, and ablue exposure frame. In an alternative implementation, the alternativepulses may include luminance (“Y”), red chrominance (“Cr”), and bluechrominance “(Cb”) pulses of light for generating a YCbCr image frameconsisting of luminance data, red chrominance data, and blue chrominancedata. The color image frame further may further data from a fluorescenceexposure frame overlaid on the RGB or YCbCr image frame. Thefluorescence pulse may include one or more pulses of electromagneticradiation for fluorescing a reagent or dye. In an embodiment, thefluorescence emission includes one or more of electromagnetic radiationhaving a wavelength from about 770 nm to about 790 nm or from about 795nm to about 815. Alternating the wavelengths of the pulsedelectromagnetic radiation allows the full pixel array to be exploitedand avoids the artifacts introduced by Bayer pattern pixel arrays.

In some instances, it is desirable to generate endoscopic imaging withmultiple data types or multiple images overlaid on one another. Forexample, it may be desirable to generate a color (Red Green Blue “RGB”)image that further includes fluorescence imaging data overlaid on theRGB image. An overlaid image of this nature may enable a medicalpractitioner or computer program to identify critical body structuresbased on the fluorescence imaging data. Historically, this would requirethe use of multiple sensor systems including an image sensor for colorimaging and one or more additional image sensors for fluorescenceimaging. In such systems, the multiple image sensors would have multipletypes of pixel sensors that are each sensitive to distinct ranges ofelectromagnetic radiation. In systems known in the art, this includesthe three separate types of pixel sensors for generating an RGB colorimage along with additional pixel sensors for generating thefluorescence image data at different wavelengths of the electromagneticspectrum. These multiple different pixel sensors consume a prohibitivelylarge physical space and cannot be located at a distal tip of theendoscope. In systems known in the art, the camera or cameras are notplaced at the distal tip of the endoscope and are instead placed in anendoscope handpiece or robotic unit. This introduces numerousdisadvantages and causes the endoscope to be very delicate. The delicateendoscope may be damaged and image quality may be degraded when theendoscope is bumped or impacted during use. Considering the foregoing,disclosed herein are systems, methods, and devices for endoscopicimaging in a light deficient environment. The systems, methods, anddevices disclosed herein provide means for employing multiple imagingtechniques in a single imaging session while permitting one or moreimage sensors to be disposed in a distal tip of the endoscope.

Fluorescence Imaging

The systems, methods, and devices disclosed herein provide means forgenerating fluorescence imaging data in a light deficient environment.The fluorescence imaging data may be used to identify certain materials,tissues, components, or processes within a body cavity or other lightdeficient environment. In certain embodiments, fluorescence imaging isprovided to a medical practitioner or computer-implemented program toenable the identification of certain structures or tissues within abody. Such fluorescence imaging data may be overlaid on black-and-whiteor RGB images to provide additional information and context.

Fluorescence is the emission of light by a substance that has absorbedlight or other electromagnetic radiation. Certain fluorescent materialsmay “glow” or emit a distinct color that is visible to the human eyewhen the fluorescent material is subjected to ultraviolet light or otherwavelengths of electromagnetic radiation. Certain fluorescent materialswill cease to glow nearly immediately when the radiation source stops.

Fluorescence occurs when an orbital electron of a molecule, atom, ornanostructure is excited by light or other electromagnetic radiation,and then relaxes to its ground state by emitting a photon from theexcited state. The specific frequencies of electromagnetic radiationthat excite the orbital electron, or are emitted by the photon duringrelaxation, are dependent on the particular atom, molecule, ornanostructure. In most cases, the light emitted by the substance has alonger wavelength, and therefore lower energy, than the radiation thatwas absorbed by the substance. However, when the absorbedelectromagnetic radiation is intense, it is possible for one electron toabsorb two photons. This two-photon absorption can lead to emission ofradiation having a shorter wavelength, and therefore higher energy, thanthe absorbed radiation. Additionally, the emitted radiation may also bethe same wavelength as the absorbed radiation.

Fluorescence imaging has numerous practical applications, includingmineralogy, gemology, medicine, spectroscopy for chemical sensors,detecting biological processes or signals, and so forth. Fluorescencemay particularly be used in biochemistry and medicine as anon-destructive means for tracking or analyzing biological molecules.The biological molecules, including certain tissues or structures, maybe tracked by analyzing the fluorescent emission of the biologicalmolecules after being excited by a certain wavelength of electromagneticradiation. However, relatively few cellular components are naturallyfluorescent. In certain implementations, it may be desirable tovisualize a certain tissue, structure, chemical process, or biologicalprocess that is not intrinsically fluorescent. In such animplementation, the body may be administered a dye or reagent that mayinclude a molecule, protein, or quantum dot having fluorescentproperties. The reagent or dye may then fluoresce after being excited bya certain wavelength of electromagnetic radiation. Different reagents ordyes may include different molecules, proteins, and/or quantum dots thatwill fluoresce at particular wavelengths of electromagnetic radiation.Thus, it may be necessary to excite the reagent or dye with aspecialized band of electromagnetic radiation to achieve fluorescenceand identify the desired tissue, structure, or process in the body.

Fluorescence imaging may provide valuable information in the medicalfield that may be used for diagnostic purposes and/or may be visualizedin real-time during a medical procedure. Specialized reagents or dyesmay be administered to a body to fluoresce certain tissues, structures,chemical processes, or biological processes. The fluorescence of thereagent or dye may highlight body structures such as blood vessels,nerves, particular organs, and so forth. Additionally, the fluorescenceof the reagent or dye may highlight conditions or diseases such ascancerous cells or cells experiencing a certain biological or chemicalprocess that may be associated with a condition or disease. Thefluorescence imaging may be used in real-time by a medical practitioneror computer program for differentiating between, for example, cancerousand non-cancerous cells during a surgical tumor extraction. Thefluorescence imaging may further be used as a non-destructive means fortracking and visualizing over time a condition in the body that wouldotherwise not be visible by the human eye or distinguishable in an RGBimage.

The systems, methods, and devices for generating fluorescence imagingdata may be used in coordination with reagents or dyes. Some reagents ordyes are known to attach to certain types of tissues and fluoresce atspecific wavelengths of the electromagnetic spectrum. In animplementation, a reagent or dye is administered to a patient that isconfigured to fluoresce when activated by certain wavelengths of light.The endoscopic imaging system disclosed herein is used to excite andfluoresce the reagent or dye. The fluorescence of the reagent or dye iscaptured by the endoscopic imaging system to aid in the identificationof tissues or structures in the body cavity. In an implementation, apatient is administered a plurality of reagents or dyes that are eachconfigured to fluoresce at different wavelengths and/or provide anindication of different structures, tissues, chemical reactions,biological processes, and so forth. In such an implementation, theendoscopic imaging system emits each of the applicable wavelengths tofluoresce each of the applicable reagents or dyes. This may negate theneed to perform individual imaging procedures for each of the pluralityof reagents or dyes.

Imaging reagents can enhance imaging capabilities in pharmaceutical,medical, biotechnology, diagnostic, and medical procedure industries.Many imaging techniques such as X-ray, computer tomography (CT),ultrasound, magnetic resonance imaging (MRI), and nuclear medicine,mainly analyze anatomy and morphology and are unable to detect changesat the molecular level. Fluorescent reagents, dyes, and probes,including quantum dot nanoparticles and fluorescent proteins, assistmedical imaging technologies by providing additional information aboutcertain tissues, structures, chemical processes, and/or biologicalprocesses that are present within the imaging region. Imaging usingfluorescent reagents enables cell tracking and/or the tracking ofcertain molecular biomarkers. Fluorescent reagents may be applied forimaging cancer, infection, inflammation, stem cell biology, and others.Numerous fluorescent reagents and dyes are being developed and appliedfor visualizing and tracking biological processes in a non-destructivemanner. Such fluorescent reagents may be excited by a certain wavelengthor band of wavelengths of electromagnetic radiation. Similarly, thosefluorescent reagents may emit relaxation energy at a certain wavelengthor band of wavelengths when fluorescing, and the emitted relaxationenergy may be read by a sensor to determine the location and/orboundaries of the reagent or dye.

In an embodiment of the disclosure, an endoscopic imaging system pulseselectromagnetic radiation for exciting an electron in a fluorescentreagent or dye. The endoscopic imaging system may pulse multipledifferent wavelengths of electromagnetic radiation for fluorescingmultiple different reagents or dyes during a single imaging session. Theendoscope includes an image sensor that is sensitive to the relaxationwavelength(s) of the one or more reagents or dyes. The imaging datagenerated by the image sensor can be used to identify a location andboundary of the one or more reagents or dyes. The endoscope system mayfurther pulse electromagnetic radiation in red, green, and blue bands ofvisible light such that the fluorescence imaging can be overlaid on anRGB video stream

Pulsed Imaging

Some implementations of the disclosure include aspects of a combinedsensor and system design that allows for high definition imaging withreduced pixel counts in a controlled illumination environment. This isaccomplished with frame-by-frame pulsing of a single-color wavelengthand switching or alternating each frame between a single, differentcolor wavelength using a controlled light source in conjunction withhigh frame capture rates and a specially designed correspondingmonochromatic sensor. Additionally, electromagnetic radiation outsidethe visible light spectrum may be pulsed to enable the generation of afluorescence image. The pixels may be color agnostic such that eachpixel generates data for each pulse of electromagnetic radiation,including pulses for red, green, and blue visible light wavelengthsalong with other wavelengths used for fluorescence imaging.

A system of the disclosure is an endoscopic imaging system for use in alight deficient environment. The system includes an endoscope comprisingan image sensor, wherein the image sensor is configured to sensereflected electromagnetic radiation for generating a plurality ofexposure frames that can be combined to generate an RGB image frame withfluorescence data overlaid thereon. The system includes an emitter foremitting pulses of electromagnetic radiation. The system includes acontroller (may alternatively be referred to as a “control circuit” inelectronic communication with the image sensor and the emitter. Thecontroller controls a duty cycle of the emitter in response to signalscorresponding to a duty cycle of the emitter. The image sensor includesbidirectional pads that can send and receive information. Thebidirectional pads of the image sensor operate in a frame period dividedinto three defined states, including a rolling readout state, a serviceline state, and a configuration state. The system includes an oscillatordisposed in the controller and a frequency detector connected to thecontroller. The frequency detector controls a clock frequency of theimage sensor in response to signals from the controller that correspondto the frequency of the oscillator. The system is such that clock signaldata is transmitted from the bidirectional pads of the image sensor tothe controller during the service line phase and the configurationphase. The system is such that exposure frames are synchronized withoutthe use of an input clock or a data transmission clock.

For the purposes of promoting an understanding of the principles inaccordance with the disclosure, reference will now be made to theembodiments illustrated in the drawings and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the disclosure is thereby intended. Anyalterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe disclosure as illustrated herein, which would normally occur to oneskilled in the relevant art and having possession of this disclosure,are to be considered within the scope of the disclosure claimed.

Before the structure, systems and methods for producing an image in alight deficient environment are disclosed and described, it is to beunderstood that this disclosure is not limited to the particularstructures, configurations, process steps, and materials disclosedherein as such structures, configurations, process steps, and materialsmay vary somewhat. It is also to be understood that the terminologyemployed herein is used for the purpose of describing particularembodiments only and is not intended to be limiting since the scope ofthe disclosure will be limited only by the appended claims andequivalents thereof.

In describing and claiming the subject matter of the disclosure, thefollowing terminology will be used in accordance with the definitionsset out below.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise.

As used herein, the terms “comprising,” “including,” “containing,”“characterized by,” and grammatical equivalents thereof are inclusive oropen-ended terms that do not exclude additional, unrecited elements ormethod steps.

As used herein, the phrase “consisting of” and grammatical equivalentsthereof exclude any element or step not specified in the claim.

As used herein, the phrase “consisting essentially of” and grammaticalequivalents thereof limit the scope of a claim to the specifiedmaterials or steps and those that do not materially affect the basic andnovel characteristic or characteristics of the claimed disclosure.

As used herein, the term “proximal” shall refer broadly to the conceptof a portion nearest an origin.

As used herein, the term “distal” shall generally refer to the oppositeof proximal, and thus to the concept of a portion farther from anorigin, or a furthest portion, depending upon the context.

As used herein, color sensors or multi spectrum sensors are thosesensors known to have a color filter array (CFA) thereon to filter theincoming electromagnetic radiation into its separate components. In thevisual range of the electromagnetic spectrum, such a CFA may be built ona Bayer pattern or modification thereon to separate green, red and bluespectrum components of the light.

As used herein, monochromatic sensor refers to an unfiltered imagingsensor. Since the pixels are color agnostic, the effective spatialresolution is appreciably higher than for their color (typicallyBayer-pattern filtered) counterparts in conventional single-sensorcameras. Monochromatic sensors may also have higher quantum efficiencybecause fewer incident photons are wasted between individual pixels.

As used herein, an emitter is a device that is capable of generating andemitting electromagnetic pulses. Various embodiments of emitters may beconfigured to emit pulses and have very specific frequencies or rangesof frequencies from within the entire electromagnetic spectrum. Pulsesmay comprise wavelengths from the visible and non-visible ranges. Anemitter may be cycled on and off to produce a pulse or may produce apulse with a shutter mechanism. An emitter may have variable poweroutput levels or may be controlled with a secondary device such as anaperture or filter. An emitter may emit broad spectrum or full spectrumelectromagnetic radiation that may produce pulses through colorfiltering or shuttering. An emitter may comprise a plurality ofelectromagnetic sources that act individually or in concert.

It should be noted that as used herein the term “light” is both aparticle and a wavelength and is intended to denote electromagneticradiation that is detectable by a pixel array 122 and may includewavelengths from the visible and non-visible spectrums ofelectromagnetic radiation. The term “partition” is used herein to mean apre-determined range of wavelengths of the electromagnetic spectrum thatis less than the entire spectrum, or in other words, wavelengths thatmake up some portion of the electromagnetic spectrum. As used herein, anemitter is a light source that may be controllable as to the portion ofthe electromagnetic spectrum that is emitted or that may operate as tothe physics of its components, the intensity of the emissions, or theduration of the emission, or all the above. An emitter may emit light inany dithered, diffused, or collimated emission and may be controlleddigitally or through analog methods or systems. As used herein, anelectromagnetic emitter is a source of a burst of electromagnetic energyand includes light sources, such as lasers, LEDs, incandescent light, orany light source that can be digitally controlled.

Referring now to the figures, FIG. 1 illustrates a schematic diagram ofa system 100 for sequential pulsed imaging in a light deficientenvironment. The system 100 can be deployed to generate an RGB imagewith fluorescence imaging data overlaid on the RGB image. The system 100includes an emitter 102 and a pixel array 122. The emitter 102 pulses apartition of electromagnetic radiation in the light deficientenvironment 112 and the pixel array 122 senses instances of reflectedelectromagnetic radiation. The emitter 102 and the pixel array 122 workin sequence such that one or more pulses of a partition ofelectromagnetic radiation results in image data sensed by the pixelarray 122.

It should be noted that as used herein the term “light” is both aparticle and a wavelength and is intended to denote electromagneticradiation that is detectable by a pixel array 122 and may includewavelengths from the visible and non-visible spectrums ofelectromagnetic radiation. The term “partition” is used herein to mean apre-determined range of wavelengths of the electromagnetic spectrum thatis less than the entire spectrum, or in other words, wavelengths thatmake up some portion of the electromagnetic spectrum. As used herein, anemitter is a light source that may be controllable as to the portion ofthe electromagnetic spectrum that is emitted or that may operate as tothe physics of its components, the intensity of the emissions, or theduration of the emission, or all the above. An emitter may emit light inany dithered, diffused, or collimated emission and may be controlleddigitally or through analog methods or systems. As used herein, anelectromagnetic emitter is a source of a burst of electromagnetic energyand includes light sources, such as lasers, LEDs, incandescent light, orany light source that can be digitally controlled.

A pixel array 122 of an image sensor may be paired with the emitter 102electronically, such that the emitter 102 and the pixel array 122 aresynced during operation for both receiving the emissions and for theadjustments made within the system. The emitter 102 may be tuned to emitelectromagnetic radiation in the form of a laser, which may be pulsed toilluminate a light deficient environment 112. The emitter 102 may pulseat an interval that corresponds to the operation and functionality ofthe pixel array 122. The emitter 102 may pulse light in a plurality ofelectromagnetic partitions such that the pixel array receiveselectromagnetic energy and produces a dataset that corresponds in timewith each specific electromagnetic partition. For example, FIG. 1illustrates an implementation wherein the emitter 102 emits fourdifferent partitions of electromagnetic radiation, including red 104,green 106, blue 108, and a fluorescence excitation 110 wavelength. Thefluorescence excitation 110 wavelength may include a plurality ofdifferent partitions of electromagnetic radiation that are selected tofluoresce a plurality of fluorescent reagents that are present withinthe light deficient environment 112. The fluorescent excitation 110wavelength may be selected to fluoresce a particular fluorescent reagentthat is present in the light deficient environment 112.

In an alternative embodiment not illustrated in FIG. 1, the pulsedemissions of light include a luminance (“Y”) emission, a red chrominance(“Cr”) emission, and a blue chrominance (“Cb”) emission in place of thepulsed red 104, pulsed green 106, and pulsed blue 108 emissions. In anembodiment, the controller or the emitter 102 modules the pulses ofelectromagnetic radiation to provide luminance and/or chrominanceinformation according to color transformation coefficients that convertlight energy from red, green, and blue light energy spaces to luminance,red chrominance, and blue chrominance light energy space. The pulsedemissions of light may further include modulated blue chrominance(“□Y+Cb”) pulses and/or modulated red chrominance (“□Y+Cr”) pulses.

The light deficient environment 112 includes structures, tissues, andother elements that reflect a combination of red 114, green 116, and/orblue 118 light. A structure that is perceived as being red 114 willreflect back pulsed red 104 light. The reflection off the red structureresults in sensed red 105 by the pixel array 122 following the pulsedred 104 emission. The data sensed by the pixel array 122 results in ared exposure frame. A structure that is perceived as being green 116will reflect back pulsed green 106 light. The reflection off the greenstructure results in sensed green 107 by the pixel array 122 followingthe pulsed green 106 emission. The data sensed by the pixel array 122results in a green exposure frame. A structure that is perceived asbeing blue 118 will reflect back pulsed blue 108 light. The reflectionoff the blue structure results in sensed blue 109 by the pixel array 122following the pulsed blue 108 emission. The data sensed by the pixelarray 122 results in a blue exposure frame.

When a structure is a combination of colors, the structure will reflectback a combination of the pulsed red 104, pulsed green 106, and/orpulsed blue 108 emissions. For example, a structure that is perceived asbeing purple will reflect back light from the pulsed red 104 and pulsedblue 108 emissions. The resulting data sensed by the pixel array 122will indicate that light was reflected in the same region following thepulsed red 104 and pulsed blue 108 emissions. When the resultant redexposure frame and blue exposure frames are combined to form the RGBimage frame, the RGB image frame will indicate that the structure ispurple.

In an embodiment where the light deficient environment 112 includes afluorescent reagent or dye or includes one or more fluorescentstructures, tissues, or other elements, the pulsing scheme may includethe emission of a certain fluorescence excitation wavelength. Thecertain fluorescence excitation wavelength may be selected to fluorescea known fluorescent reagent, dye, or other structure. The fluorescentstructure will be sensitive to the fluorescence excitation wavelengthand will emit a fluorescence relaxation wavelength. The fluorescencerelaxation wavelength will be sensed by the pixel array 122 followingthe emission of the fluorescence excitation wavelength. The data sensedby the pixel array 122 results in a fluorescence exposure frame. Thefluorescence exposure frame may be combined with multiple other exposureframes to form an image frame. The data in the fluorescence exposureframe may be overlaid on an RGB image frame that includes data from ared exposure frame, a green exposure frame, and a blue exposure frame.

In an embodiment where the light deficient environment 112 includesstructures, tissues, or other materials that emit a spectral response tocertain partitions of the electromagnetic spectrum, the pulsing schememay include the emission of a hyperspectral partition of electromagneticradiation for the purpose of eliciting the spectral response from thestructures, tissues, or other materials present in the light deficientenvironment 112. The spectral response includes the emission orreflection of certain wavelengths of electromagnetic radiation. Thespectral response can be sensed by the pixel array 122 and result in ahyperspectral exposure frame. The hyperspectral exposure frame may becombined with multiple other exposure frames to form an image frame. Thedata in the hyperspectral exposure frame may be overlaid on an RGB imageframe that includes data from a red exposure frame, a green exposureframe, and a blue exposure frame.

In an embodiment, the pulsing scheme includes the emission of a lasermapping or tool tracking pattern. The reflected electromagneticradiation sensed by the pixel array 122 following the emission of thelaser mapping or tool tracking pattern results in a laser mappingexposure frame. The data in the laser mapping exposure frame may beprovided to a corresponding system to identify, for example, distancesbetween tools present in the light deficient environment 112, athree-dimensional surface topology of a scene in the light deficientenvironment 112, distances, dimensions, or positions of structures orobjects within the scene, and so forth. This data may be overlaid on anRGB image frame or otherwise provided to a user of the system.

The emitter 102 may be a laser emitter that is capable of emittingpulsed red 104 light for generating sensed red 105 data for identifyingred 114 elements within the light deficient environment 112. The emitter102 is further capable of emitting pulsed green 106 light for generatingsensed green 107 data for identifying green 116 elements within thelight deficient environment. The emitter 102 is further capable ofemitting pulsed blue 108 light for generating sensed blue 109 data foridentifying blue 118 elements within the light deficient environment.The emitter 102 is further capable of emitting pulsed fluorescenceexcitation 110 wavelength(s) of electromagnetic radiation foridentifying a fluorescent reagent 120 within the light deficientenvironment 112. The fluorescent reagent 120 is identified by excitingthe fluorescent reagent 120 with the pulsed fluorescence excitation 110light and then sensing (by the pixel array 122) the fluorescencerelaxation 111 wavelength for that particular fluorescent reagent 120.The emitter 102 is capable of emitting the pulsed red 104, pulsed green106, pulsed blue 108, and pulsed fluorescence excitation 110 wavelengthsin any desired sequence.

The pixel array 122 senses reflected electromagnetic radiation. Each ofthe sensed red 105, the sensed green 107, the sensed blue 109, and thesensed fluorescence relaxation 111 data can be referred to as an“exposure frame.” Each exposure frame is assigned a specific color orwavelength partition, wherein the assignment is based on the timing ofthe pulsed color or wavelength partition from the emitter 102. Theexposure frame in combination with the assigned specific color orwavelength partition may be referred to as a dataset. Even though thepixels 122 are not color-dedicated, they can be assigned a color for anygiven dataset based on a priori information about the emitter.

For example, during operation, after pulsed red 104 light is pulsed inthe light deficient environment 112, the pixel array 122 sensesreflected electromagnetic radiation. The reflected electromagneticradiation results in an exposure frame, and the exposure frame iscatalogued as sensed red 105 data because it corresponds in time withthe pulsed red 104 light. The exposure frame in combination with anindication that it corresponds in time with the pulsed red 104 light isthe “dataset.” This is repeated for each partition of electromagneticradiation emitted by the emitter 102. The data created by the pixelarray 122 includes the sensed red 105 exposure frame identifying red 114components in the light deficient environment and corresponding in timewith the pulsed red 104 light. The data further includes the sensedgreen 107 exposure frame identifying green 116 components in the lightdeficient environment and corresponding in time with the pulsed green106 light. The data further includes the sensed blue 109 exposure frameidentifying blue 118 components in the light deficient environment andcorresponding in time with the pulsed blue 108 light. The data furtherincludes the sensed fluorescence relaxation 111 exposure frameidentifying the fluorescent reagent 120 and corresponding in time withthe pulsed fluorescence excitation 110 wavelength(s) of light.

In one embodiment, three datasets representing RED, GREEN and BLUEelectromagnetic pulses are combined to form a single image frame. Thus,the information in a red exposure frame, a green exposure frame, and ablue exposure frame are combined to form a single RGB image frame. Oneor more additional datasets representing other wavelength partitions maybe overlaid on the single RGB image frame. The one or more additionaldatasets may represent, for example, fluorescence imaging responsive tothe pulsed excitation 110 wavelength between 770 nm and 790 nm andbetween 795 nm and 815 nm.

It will be appreciated that the disclosure is not limited to anyparticular color combination or any particular electromagneticpartition, and that any color combination or any electromagneticpartition may be used in place of RED, GREEN and BLUE, such as Cyan,Magenta and Yellow; Ultraviolet; infrared; any combination of theforegoing, or any other color combination, including all visible andnon-visible wavelengths, without departing from the scope of thedisclosure. In the figure, the light deficient environment 112 to beimaged includes red 114, green 116, and blue 118 portions, and furtherincludes a fluorescent reagent 120. As illustrated in the figure, thereflected light from the electromagnetic pulses only contains the datafor the portion of the object having the specific color that correspondsto the pulsed color partition. Those separate color (or color interval)datasets can then be used to reconstruct the image by combining thedatasets at 126. The information in each of the multiple exposure frames(i.e., the multiple datasets) may be combined by a controller 124, acontrol unit, a camera control unit, the image sensor, an image signalprocessing pipeline, or some other computing resource that isconfigurable to process the multiple exposure frames and combine thedatasets at 126. The datasets may be combined to generate the singleimage frame within the endoscope unit itself or offsite by some otherprocessing resource.

FIG. 2 is a system 200 for providing illumination to a light deficientenvironment, such as for endoscopic imaging. The system 200 may be usedin combination with any of the systems, methods, or devices disclosedherein. The system 200 includes an emitter 202, a controller 204, ajumper waveguide 206, a waveguide connector 208, a lumen waveguide 210,a lumen 212, and an image sensor 214 with accompanying opticalcomponents (such as a lens). The emitter 202 (may be genericallyreferred to as a “light source”) generates light that travels throughthe jumper waveguide 206 and the lumen waveguide 210 to illuminate ascene at a distal end of the lumen 212. The emitter 202 may be used toemit any wavelength of electromagnetic energy including visiblewavelengths, infrared, ultraviolet, hyperspectral, fluorescenceexcitation, laser mapping pulsing schemes, or other wavelengths. Thelumen 212 may be inserted into a patient's body for imaging, such asduring a procedure or examination. The light is output as illustrated bydashed lines 216. A scene illuminated by the light may be captured usingthe image sensor 214 and displayed for a doctor or some other medicalpersonnel. The controller 204 may provide control signals to the emitter202 to control when illumination is provided to a scene. In oneembodiment, the emitter 202 and controller 204 are located within acamera control unit (CCU) or external console to which an endoscope isconnected. If the image sensor 214 includes a CMOS sensor, light may beperiodically provided to the scene in a series of illumination pulsesbetween readout periods of the image sensor 214 during what is known asa blanking period. Thus, the light may be pulsed in a controlled mannerto avoid overlapping into readout periods of the image pixels in a pixelarray of the image sensor 214.

In one embodiment, the lumen waveguide 210 includes one or more opticalfibers. The optical fibers may be made of a low-cost material, such asplastic to allow for disposal of the lumen waveguide 210 and/or otherportions of an endoscope. In one embodiment, the lumen waveguide 210 isa single glass fiber having a diameter of 500 microns. The jumperwaveguide 206 may be permanently attached to the emitter 202. Forexample, a jumper waveguide 206 may receive light from an emitter withinthe emitter 202 and provide that light to the lumen waveguide 210 at thelocation of the connector 208. In one embodiment, the jumper waveguide106 includes one or more glass fibers. The jumper waveguide may includeany other type of waveguide for guiding light to the lumen waveguide210. The connector 208 may selectively couple the jumper waveguide 206to the lumen waveguide 210 and allow light within the jumper waveguide206 to pass to the lumen waveguide 210. In one embodiment, the lumenwaveguide 210 is directly coupled to a light source without anyintervening jumper waveguide 206.

The image sensor 214 includes a pixel array. In an embodiment, the imagesensor 214 includes two or more pixel arrays for generating athree-dimensional image. The image sensor 214 may constitute two moreimage sensors that each have an independent pixel array and can operateindependent of one another. The pixel array of the image sensor 214includes active pixels and optical black (“OB”) or optically blindpixels. The active pixels may be clear “color agnostic” pixels that arecapable of sensing imaging data for any wavelength of electromagneticradiation. The optical black pixels are read during a blanking period ofthe pixel array when the pixel array is “reset” or calibrated. In anembodiment, light is pulsed during the blanking period of the pixelarray when the optical black pixels are being read. After the opticalblack pixels have been read, the active pixels are read during a readoutperiod of the pixel array. The active pixels may be charged by theelectromagnetic radiation that is pulsed during the blanking period suchthat the active pixels are ready to be read by the image sensor duringthe readout period of the pixel array.

FIG. 2A is a schematic diagram of complementary system hardware such asa special purpose or general-purpose computer. Implementations withinthe scope of the present disclosure may also include physical and othernon-transitory computer readable media for carrying or storing computerexecutable instructions and/or data structures. Such computer readablemedia can be any available media that can be accessed by a generalpurpose or special purpose computer system. Computer readable media thatstores computer executable instructions are computer storage media(devices). Computer readable media that carry computer executableinstructions are transmission media. Thus, by way of example, and notlimitation, implementations of the disclosure can comprise at least twodistinctly different kinds of computer readable media: computer storagemedia (devices) and transmission media.

Computer storage media (devices) includes RAM, ROM, EEPROM, CD-ROM,solid state drives (“SSDs”) (e.g., based on RAM), Flash memory,phase-change memory (“PCM”), other types of memory, other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to store desired program code means inthe form of computer executable instructions or data structures andwhich can be accessed by a general purpose or special purpose computer.

A “network” is defined as one or more data links that enable thetransport of electronic data between computer systems and/or modulesand/or other electronic devices. In an implementation, a sensor andcamera control unit may be networked to communicate with each other, andother components, connected over the network to which they areconnected. When information is transferred or provided over a network oranother communications connection (either hardwired, wireless, or acombination of hardwired or wireless) to a computer, the computerproperly views the connection as a transmission medium. Transmissionsmedia can include a network and/or data links, which can be used tocarry desired program code means in the form of computer executableinstructions or data structures and which can be accessed by a generalpurpose or special purpose computer. Combinations of the above shouldalso be included within the scope of computer readable media.

Further, upon reaching various computer system components, program codemeans in the form of computer executable instructions or data structuresthat can be transferred automatically from transmission media tocomputer storage media (devices) (or vice versa). For example, computerexecutable instructions or data structures received over a network ordata link can be buffered in RAM within a network interface module(e.g., a “NIC”), and then eventually transferred to computer system RAMand/or to less volatile computer storage media (devices) at a computersystem. RAM can also include solid state drives (SSDs or PCIx based realtime memory tiered storage, such as FusionIO). Thus, it should beunderstood that computer storage media (devices) can be included incomputer system components that also (or even primarily) utilizetransmission media.

Computer executable instructions comprise, for example, instructions anddata which, when executed by one or more processors, cause ageneral-purpose computer, special purpose computer, or special purposeprocessing device to perform a certain function or group of functions.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, or evensource code. Although the subject matter has been described in languagespecific to structural features and/or methodological acts, it is to beunderstood that the subject matter defined in the appended claims is notnecessarily limited to the described features or acts described above.Rather, the described features and acts are disclosed as example formsof implementing the claims.

Those skilled in the art will appreciate that the disclosure may bepracticed in network computing environments with many types of computersystem configurations, including, personal computers, desktop computers,laptop computers, message processors, control units, camera controlunits, hand-held devices, hand pieces, multi-processor systems,microprocessor-based or programmable consumer electronics, network PCs,minicomputers, mainframe computers, mobile telephones, PDAs, tablets,pagers, routers, switches, various storage devices, and the like. Itshould be noted that any of the above-mentioned computing devices may beprovided by or located within a brick and mortar location. Thedisclosure may also be practiced in distributed system environmentswhere local and remote computer systems, which are linked (either byhardwired data links, wireless data links, or by a combination ofhardwired and wireless data links) through a network, both performtasks. In a distributed system environment, program modules may belocated in both local and remote memory storage devices.

Further, where appropriate, functions described herein can be performedin one or more of: hardware, software, firmware, digital components, oranalog components. For example, one or more application specificintegrated circuits (ASICs) or field programmable gate arrays (FPGAs)can be programmed to carry out one or more of the systems and proceduresdescribed herein. Certain terms are used throughout the followingdescription and Claims to refer to particular system components. As oneskilled in the art will appreciate, components may be referred to bydifferent names. This document does not intend to distinguish betweencomponents that differ in name, but not function.

FIG. 2A is a block diagram illustrating an example computing device 250.Computing device 250 may be used to perform various procedures, such asthose discussed herein. Computing device 250 can function as a server, aclient, or any other computing entity. Computing device 250 can performvarious monitoring functions as discussed herein, and can execute one ormore application programs, such as the application programs describedherein. Computing device 250 can be any of a wide variety of computingdevices, such as a desktop computer, a notebook computer, a servercomputer, a handheld computer, camera control unit, tablet computer andthe like.

Computing device 250 includes one or more processor(s) 252, one or morememory device(s) 254, one or more interface(s) 256, one or more massstorage device(s) 258, one or more Input/Output (I/O) device(s) 260, anda display device 280 all of which are coupled to a bus 262. Processor(s)252 include one or more processors or controllers that executeinstructions stored in memory device(s) 254 and/or mass storagedevice(s) 258. Processor(s) 252 may also include various types ofcomputer readable media, such as cache memory.

Memory device(s) 254 include various computer readable media, such asvolatile memory (e.g., random access memory (RAM) 264) and/ornonvolatile memory (e.g., read-only memory (ROM) 266). Memory device(s)254 may also include rewritable ROM, such as Flash memory.

Mass storage device(s) 258 include various computer readable media, suchas magnetic tapes, magnetic disks, optical disks, solid-state memory(e.g., Flash memory), and so forth. As shown in FIG. 2, a particularmass storage device is a hard disk drive 274. Various drives may also beincluded in mass storage device(s) 258 to enable reading from and/orwriting to the various computer readable media. Mass storage device(s)258 include removable media 276 and/or non-removable media.

I/O device(s) 260 include various devices that allow data and/or otherinformation to be input to or retrieved from computing device 250.Example I/O device(s) 260 include digital imaging devices,electromagnetic sensors and emitters, cursor control devices, keyboards,keypads, microphones, monitors or other display devices, speakers,printers, network interface cards, modems, lenses, CCDs or other imagecapture devices, and the like.

Display device 280 includes any type of device capable of displayinginformation to one or more users of computing device 250. Examples ofdisplay device 280 include a monitor, display terminal, video projectiondevice, and the like.

Interface(s) 256 include various interfaces that allow computing device250 to interact with other systems, devices, or computing environments.Example interface(s) 256 may include any number of different networkinterfaces 270, such as interfaces to local area networks (LANs), widearea networks (WANs), wireless networks, and the Internet. Otherinterface(s) include user interface 268 and peripheral device interface272. The interface(s) 256 may also include one or more user interfaceelements 268. The interface(s) 256 may also include one or moreperipheral interfaces such as interfaces for printers, pointing devices(mice, track pad, etc.), keyboards, and the like.

Bus 262 allows processor(s) 252, memory device(s) 254, interface(s) 256,mass storage device(s) 258, and I/O device(s) 260 to communicate withone another, as well as other devices or components coupled to bus 262.Bus 262 represents one or more of several types of bus structures, suchas a system bus, PCI bus, IEEE 1394 bus, USB bus, and so forth.

For purposes of illustration, programs and other executable programcomponents are shown herein as discrete blocks, although it isunderstood that such programs and components may reside at various timesin different storage components of computing device 250 and are executedby processor(s) 252. Alternatively, the systems and procedures describedherein can be implemented in hardware, or a combination of hardware,software, and/or firmware. For example, one or more application specificintegrated circuits (ASICs) or field programmable gate arrays (FPGAs)can be programmed to carry out one or more of the systems and proceduresdescribed herein.

FIG. 3A illustrates the operational cycles of a sensor used in rollingreadout mode or during the sensor readout 300. The frame readout periodmay start at and may be represented by vertical line 310. The readoutperiod 302 is represented by the diagonal or slanted line. The sensormay be read out on a row by row basis, the top of the downwards slantededge being the sensor top row 312 and the bottom of the downwardsslanted edge being the sensor bottom row 314. The time between the lastrow readout and the next readout period may be called the blankingperiod 316. It should be noted that some of the sensor pixel rows mightbe covered with a light shield (e.g., a metal coating or any othersubstantially black layer of another material type). These covered pixelrows may be referred to as optical black rows 318 and 320. Optical blackrows 318 and 320 may be used as input for correction algorithms. Asshown in FIG. 3A, these optical black rows 318 and 320 may be located onthe top of the pixel array or at the bottom of the pixel array or at thetop and the bottom of the pixel array.

FIG. 3B illustrates a process of controlling the amount ofelectromagnetic radiation, e.g., light, that is exposed to a pixel,thereby integrated or accumulated by the pixel. It will be appreciatedthat photons are elementary particles of electromagnetic radiation.Photons are integrated, absorbed, or accumulated by each pixel andconverted into an electrical charge or current. An electronic shutter orrolling shutter (shown by dashed line 322) may be used to start theintegration time by resetting the pixel. The light will then integrateuntil the next readout period. The position of the electronic shutter322 can be moved between two readout periods 302 to control the pixelsaturation for a given amount of light. It should be noted that thistechnique allows for a constant integration time between two differentlines but introduces a delay when moving from top to bottom rows.

FIG. 3C illustrates the case where the electronic shutter 322 has beenremoved. In this configuration, the integration of the incoming lightmay start during the readout period 302 and may end at the next readoutperiod 302, which also defines the start of the next integration.

FIG. 3D shows a configuration without an electronic shutter 322, butwith a controlled and pulsed light 330 during the blanking period 316.This ensures that all rows see the same light issued from the same lightpulse 330. In other words, each row will start its integration in a darkenvironment, which may be at the optical black back row 320 of read outframe (m) for a maximum light pulse width, and will then receive a lightstrobe and will end its integration in a dark environment, which may beat the optical black front row 318 of the next succeeding read out frame(m+1) for a maximum light pulse width. In the FIG. 3D example, the imagegenerated from the light pulse will be solely available during frame(m+1) readout without any interference with frames (m) and (m+2). Itshould be noted that the condition to have a light pulse to be read outonly in one frame and not interfere with neighboring frames is to havethe given light pulse firing during the blanking period 316. Because theoptical black rows 318, 320 are insensitive to light, the optical blackback rows 320 time of frame (m) and the optical black front rows 318time of frame (m+1) can be added to the blanking period 316 to determinethe maximum range of the firing time of the light pulse 330.

As illustrated in the FIG. 3A, a sensor may be cycled many times toreceive data for each pulsed color or wavelength (e.g., Red, Green,Blue, or other wavelength on the electromagnetic spectrum). Each cyclemay be timed. In an embodiment, the cycles may be timed to operatewithin an interval of 16.67 ms. In another embodiment, the cycles may betimed to operate within an interval of 8.3 ms. It will be appreciatedthat other timing intervals are contemplated by the disclosure and areintended to fall within the scope of this disclosure.

FIG. 4A graphically illustrates the operation of an embodiment of anelectromagnetic emitter. An emitter may be timed to correspond with thecycles of a sensor, such that electromagnetic radiation is emittedwithin the sensor operation cycle and/or during a portion of the sensoroperation cycle. FIG. 4A illustrates Pulse 1 at 402, Pulse 2 at 404, andPulse 3 at 406. In an embodiment, the emitter may pulse during thereadout period 302 of the sensor operation cycle. In an embodiment, theemitter may pulse during the blanking period 316 of the sensor operationcycle. In an embodiment, the emitter may pulse for a duration that isduring portions of two or more sensor operational cycles. In anembodiment, the emitter may begin a pulse during the blanking period316, or during the optical black portion 320 of the readout period 302,and end the pulse during the readout period 302, or during the opticalblack portion 318 of the readout period 302 of the next succeedingcycle. It will be understood that any combination of the above isintended to fall within the scope of this disclosure as long as thepulse of the emitter and the cycle of the sensor correspond.

FIG. 4B graphically represents varying the duration and magnitude of theemitted electromagnetic pulse (e.g., Pulse 1 at 412, Pulse 2 at 414, andPulse 3 at 416) to control exposure. An emitter having a fixed outputmagnitude may be pulsed during any of the cycles noted above in relationto FIGS. 3D and 4A for an interval to provide the needed electromagneticenergy to the pixel array. An emitter having a fixed output magnitudemay be pulsed at a longer interval of time, thereby providing moreelectromagnetic energy to the pixels or the emitter may be pulsed at ashorter interval of time, thereby providing less electromagnetic energy.Whether a longer or shorter interval time is needed depends upon theoperational conditions.

In contrast to adjusting the interval of time the emitter pulses a fixedoutput magnitude, the magnitude of the emission itself may be increasedto provide more electromagnetic energy to the pixels. Similarly,decreasing the magnitude of the pulse provides less electromagneticenergy to the pixels. It should be noted that an embodiment of thesystem may have the ability to adjust both magnitude and durationconcurrently, if desired. Additionally, the sensor may be adjusted toincrease its sensitivity and duration as desired for optimal imagequality. FIG. 4B illustrates varying the magnitude and duration of thepulses. In the illustration, Pulse 1 at 412 has a higher magnitude orintensity than either Pulse 2 at 414 or Pulse 3 at 416. Additionally,Pulse 1 at 412 has a shorter duration than Pulse 2 at 414 or Pulse 3 at416, such that the electromagnetic energy provided by the pulse isillustrated by the area under the pulse shown in the illustration. Inthe illustration, Pulse 2 at 414 has a relatively low magnitude orintensity and a longer duration when compared to either Pulse 1 at 412or Pulse 3 at 416. Finally, in the illustration, Pulse 3 at 416 has anintermediate magnitude or intensity and duration, when compared to Pulse1 at 412 and Pulse 2 at 414.

FIG. 5 is a graphical representation of an embodiment of the disclosurecombining the operational cycles, the electromagnetic emitter, and theemitted electromagnetic pulses of FIGS. 3A-3D and 4A to demonstrate theimaging system during operation in accordance with the principles andteachings of the disclosure. As can be seen in the figure, theelectromagnetic emitter pulses the emissions primarily during theblanking period 316 of the image sensor such that the pixels will becharged and ready to read during the readout period 302 of the imagesensor cycle. The dashed lines in FIG. 5 represent the pulses ofelectromagnetic radiation (from FIG. 4A). The pulses of electromagneticradiation are primarily emitted during the blanking period 316 of theimage sensor but may overlap with the readout period 302 of the imagesensor.

An exposure frame includes the data read by the pixel array of the imagesensor during a readout period 302. The exposure frame may be combinedwith an indication of what type of pulse was emitted by the emitterprior to the readout period 302. The combination of the exposure frameand the indication of the pulse type may be referred to as a dataset.Multiple exposure frames may be combined to generate a black-and-whiteor RGB color image. Additionally, hyperspectral, fluorescence, and/orlaser mapping imaging data may be overlaid on a black-and-white or RGBimage.

In an embodiment, an exposure frame is the data sensed by the pixelarray during the readout period 302 that occurs subsequent to a blankingperiod 316. The emission of electromagnetic radiation is emitted duringthe blanking period 316. In an embodiment, a portion of the emission ofelectromagnetic radiation overlaps the readout period 302. The blankingperiod 316 occurs when optical black pixels of the pixel array are beingread and the readout period 302 occurs when active pixels of the pixelarray are being read. The blanking period 316 may overlap the readoutperiod 302.

FIGS. 6A and 6B illustrate processes for recording an image frame.Multiple image frames may be strung together to generate a video stream.A single image frame may include data from multiple exposure frames,wherein an exposure frame is the data sensed by a pixel array subsequentto an emission of electromagnetic radiation. FIG. 6A illustrates atraditional process that is typically implemented with a color imagesensor having a color filter array (CFA) for filtering out certainwavelengths of light per pixel. FIG. 6B is a process that is disclosedherein and can be implemented with a monochromatic “color agnostic”image sensor that is receptive to all wavelengths of electromagneticradiation.

The process illustrated in FIG. 6A occurs from time t(0) to time t(1).The process begins with a white light emission 602 and sensing whitelight 604. The image is processed and displayed at 606 based on thesensing at 604.

The process illustrated in FIG. 6B occurs from time t(0) to time t(1).The process begins with an emission of green light 612 and sensingreflected electromagnetic radiation 614 subsequent to the emission ofgreen light 612. The process continues with an emission of red light 616and sensing reflected electromagnetic radiation 618 subsequent to theemission of red light 616. The process continues with an emission ofblue light 620 and sensing reflected electromagnetic radiation 622subsequent to the emission of blue light 620. The process continues withone or more emissions of a fluorescence excitation wavelengths 624 andsensing reflected electromagnetic energy 626 subsequent to each of theone or more emissions of fluorescence excitation wavelengths ofelectromagnetic radiation 624. The image is processed and displayed at628 based on each of the sensed reflected electromagnetic energyinstances 614, 618, 622, and 626.

The process illustrated in FIG. 6B provides a higher resolution imageand provides a means for generating an RGB image that further includesfluorescence imaging data. When partitioned spectrums of light are used,(as in FIG. 6B) a sensor can be made sensitive to all wavelengths ofelectromagnetic energy. In the process illustrated in FIG. 6B, themonochromatic pixel array is instructed that it is sensingelectromagnetic energy from a predetermined partition of the fullspectrum of electromagnetic energy in each cycle. Therefore, to form animage the sensor need only be cycled with a plurality of differingpartitions from within the full spectrum of light. The final image isassembled based on the multiple cycles. Because the image from eachcolor partition frame cycle has a higher resolution (compared with a CFApixel array), the resultant image created when the partitioned lightframes are combined also has a higher resolution. In other words,because each and every pixel within the array (instead of, at most,every second pixel in a sensor with a CFA) is sensing the magnitudes ofenergy for a given pulse and a given scene, just fractions of timeapart, a higher resolution image is created for each scene.

As can be seen graphically in the embodiments illustrated in FIGS. 6Aand 6B between times t(0) and t(1), the sensor for the partitionedspectrum system in FIG. 6B has cycled at least four times for every oneof the full spectrum system in FIG. 6A. In an embodiment, a displaydevice (LCD panel) operates at 50-60 frames per second. In such anembodiment, the partitioned light system in FIG. 6B may operate at200-240 frames per second to maintain the continuity and smoothness ofthe displayed video. In other embodiments, there may be differentcapture and display frame rates. Furthermore, the average capture ratecould be any multiple of the display rate.

In an embodiment, it may be desired that not all partitions berepresented equally within the system frame rate. In other words, notall light sources have to be pulsed with the same regularity so as toemphasize and de-emphasize aspects of the recorded scene as desired bythe users. It should also be understood that non-visible and visiblepartitions of the electromagnetic spectrum may be pulsed together withina system with their respective data value being stitched into the videooutput as desired for display to a user.

An embodiment may comprise a pulse cycle pattern as follows:

-   -   i. Green pulse;    -   ii. Red pulse;    -   iii. Blue pulse;    -   iv. Green pulse;    -   v. Red pulse;    -   vi. Blue pulse;    -   vii. Fluorescence excitation pulse;    -   viii. (Repeat)

An embodiment may comprise a pulse cycle pattern as follows:

-   -   i. Luminance pulse;    -   ii. Red chrominance pulse;    -   iii. Luminance pulse;    -   iv. Blue Chrominance pulse;    -   v. Fluorescence excitation pulse;    -   vi. (Repeat)

An embodiment may comprise a pulse cycle pattern as follows:

-   -   i. Luminance pulse;    -   ii. Red chrominance pulse;    -   iii. Luminance pulse;    -   iv. Blue Chrominance pulse;    -   v. Luminance pulse;    -   vi. Red chrominance pulse;    -   vii. Luminance pulse;    -   viii. Blue Chrominance pulse;    -   ix. Fluorescence excitation pulse;    -   x. (Repeat)

As can be seen in the example, a fluorescence excitation partition maybe pulsed at a rate differing from the rates of the other partitionpulses. This may be done to emphasize a certain aspect of the scene,with the fluorescence imaging data simply being overlaid with the otherdata in the video output to make the desired emphasis. It should benoted that the addition of a fluorescence partition on top of the RED,GREEN, and BLUE partitions does not necessarily require the serializedsystem to operate at four times the rate of a full spectrum non-serialsystem because every partition does not have to be represented equallyin the pulse pattern. As seen in the embodiment, the addition of apartition pulse that is represented less in a pulse pattern(fluorescence excitation in the above example), would result in anincrease of less than 20% of the cycling speed of the sensor toaccommodate the irregular partition sampling.

In various embodiments, the pulse cycle pattern may further include anyof the following wavelengths in any suitable order. Such wavelengths maybe particularly suited for exciting a fluorescent reagent to generatefluorescence imaging data by sensing the relaxation emission of thefluorescent reagent based on a fluorescent reagent relaxation emission:

-   -   i. 770±20 nm;    -   ii. 770±10 nm;    -   iii. 770±5 nm;    -   iv. 790±20 nm;    -   v. 790±10 nm;    -   vi. 790±5 nm;    -   vii. 795±20 nm;    -   viii. 795±10 nm;    -   ix. 795±5 nm;    -   x. 815±20 nm;    -   xi. 815±10 nm;    -   xii. 815±5 nm;    -   xiii. 770 nm to 790 nm; and/or    -   xiv. 795 nm to 815 nm.

The partition cycles may be divided so as to accommodate or approximatevarious imaging and video standards. In an embodiment, the partitioncycles comprise pulses of electromagnetic energy in the Red, Green, andBlue spectrum as follows as illustrated best in FIGS. 7A-7D. The timingrelationship between the emission of pulses of electromagnetic radiationby the emitter, and the readout of the pixel array is furtherillustrated in FIGS. 7A-7D.

In FIG. 7A, the different light intensities have been achieved bymodulating the light pulse width or duration within the working rangeshown by the vertical grey dashed lines. FIG. 7A illustrates the generaltiming relationships within a four-frame cycle, between pulsed mixturesof three wavelengths and the readout cycle of the pixel array of theimage sensor. In an embodiment, there are three monochromatic pulsedlight sources under the control of the controller. Periodic sequences ofmonochromatic red, monochromatic green, and monochromatic blue exposureframes are captured, e.g. with an R-G-B-G pulsing pattern and assembledinto an sRGB image frame by the image signal processor chain.

In FIG. 7B, the different light intensities have been achieved bymodulating the light power or the power of the electromagnetic emitter,which may be a laser or LED emitter, but keeping the pulse width orduration constant.

FIG. 7C shows the case where both the light power and the light pulsewidth are being modulated, leading to greater flexibility. The partitioncycles may use Cyan Magenta Yellow (CMY), infrared, ultraviolet,hyperspectral, and fluorescence using a non-visible pulse source mixedwith visible pulse sources and any other color space required to producean image or approximate a desired video standard that is currently knownor yet to be developed. It should also be understood that a system maybe able to switch between the color spaces on the fly to provide thedesired image output quality.

In an embodiment using color spaces Green-Blue-Green-Red (as seen inFIG. 7D) it may be desirous to pulse the luminance components more oftenthan the chrominance components because users are generally moresensitive to light magnitude differences than to light colordifferences. This principle can be exploited using a monochromatic imagesensor as illustrated in FIG. 7D. In FIG. 7D, green, which contains themost luminance information, may be pulsed more often or with moreintensity in a (G-B-GR-GB-G-R . . . ) scheme to obtain the luminancedata. Such a configuration would create a video stream that hasperceptively more detail, without creating and transmittingunperceivable data.

In an embodiment, all three sources of light are pulsed in unison withlight energies that are modulated to provide pure luminance informationin the same exposure frame. The light energies may be modulatedaccording to color transformation coefficients that convert from RGBcolor space to YCbCr color space. It should be appreciated that thecolor transformation may be implemented according to any suitablestandard such as the ITU-R BT.709 HD standard, the ITU-R BT.601standard, the ITU-R BT.2020 standard, or any other suitable standard orformula. The conversion may be performed according to the ITU-R BT.709HD standard as follows:

$\begin{bmatrix}Y \\{Cb} \\{Cr}\end{bmatrix} = {\begin{bmatrix}R \\G \\B\end{bmatrix}\begin{bmatrix}0.183 & 0.614 & 0.062 \\{- 0.101} & {- 0.339} & 0.439 \\0.439 & {- 0.399} & {- 0.040}\end{bmatrix}}$

In addition to the modulation of luminance information, a full colorimage further requires the red chrominance and blue chrominancecomponents. However, the algorithm applied for the luminance componentcannot be directly applied for chrominance componence because thealgorithm is signed as reflected in the fact that some of the RGBcoefficients are negative. In an embodiment, a degree of luminance isadded so that all of the final pulse energies are a positive value. Aslong as the color fusion process in the image signal processor is awareof the composition of the chrominance exposure frames, they can bedecoded by subtracting the appropriate amount of luminance from aneighboring frame. The pulse energy proportions are given by:

Y = 0.183 ⋅ R + 0.614 ⋅ G + 0.062 ⋅ BCb = λ ⋅ Y − 0.101 ⋅ R − 0.339 ⋅ G + 0.439 ⋅ BCr = δ ⋅ Y + 0.439 ⋅ R − 0.399 ⋅ G − 0.040 ⋅ B where${\lambda \geq \frac{0.339}{0.614}} = 0.552$${\delta \geq \frac{0.399}{0.614}} = 0.650$

If the λ factor is equal to 0.552, the red and green components arecancelled. In the case, the blue chrominance information can be providedwith pure blue light. Similarly, if the δ factor is equal to 0.650, theblue and green components are cancelled, and the red chrominanceinformation can be provided with pure red light. This embodiment is aconvenient approximation for digital frame reconstruction.

In an embodiment where white balance is performed in the illuminationdomain, then the modulation is imposed in addition to the white balancemodulation.

In an embodiment, duplicating the pulse of a weaker partition may beused to produce an output that has been adjusted for the weaker pulse.For example, blue laser light is considered weak relative to thesensitivity of silicon-based pixels and is difficult to produce incomparison to the red or green light, and therefore may be pulsed moreoften during a frame cycle to compensate for the weakness of the light.These additional pulses may be done serially over time or by usingmultiple lasers that simultaneously pulse to produce the desiredcompensation effect. It should be noted that by pulsing during ablanking period (time during which the sensor is not reading out thepixel array), the sensor is insensitive to differences/mismatchesbetween lasers of the same kind and simply accumulates the light for thedesired output. In another embodiment, the maximum light pulse range maybe different from frame to frame. This is shown in FIG. 7E, where thelight pulses are different from frame to frame. The sensor may be builtto be able to program different blanking periods with a repeatingpattern of two or three or four or n frames.

In FIG. 7E, four different light pulses are illustrated, and Pulse 1 mayrepeat for example after Pulse 4 and may have a pattern of four frameswith different blanking periods. This technique can be used to place themost powerful partition on the smallest blanking period and thereforeallow the weakest partition to have wider pulse on one of the nextframes without the need of increasing the readout speed. Thereconstructed frame can still have a regular pattern from frame to frameas it is constituted of many pulsed frames.

FIGS. 8-14 illustrate various configurations for a pixel array thatalternate which subset of pixels are configured as long exposures orshort exposures. FIGS. 8-10, 12, and 14 illustrate pixel configurationsfor generating a YCbCr image frame and FIGS. 11 and 13 illustrate pixelconfigurations for generating an RGB image frame.

A YCbCr image frame may be generated according the pixel configurationsillustrated in FIGS. 8-10, 12, and 14. YCbCr image frames exist in theluminance-chrominance color space. The luminance (“Y”) componentcorresponds to the color agnostic brightness aspect of the image data.The color information is carried in the remaining two color channels,including the red chrominance (“Cr”) channel and the blue chrominance(“Cb”) channel. The luminance and chrominance components of the imagedata are separated by generating separate luminance exposure frames andchrominance exposure frames that can be combined to generate the YCbCrimage frame. The spatial resolution of an image frame is more importantfor the luminance component than for either chrominance component, andfor this reason, the luminance component may be pulsed repeatedly whengenerating a single YCbCr image frame.

FIG. 8 illustrates a pixel array 800 of an image sensor. The pixel array800 comprises a plurality of pixels arranged in a grid-like pattern. Thepixels are depicted as discrete squares in FIGS. 8-14. The pixel array800 is configured for sensing reflected electromagnetic radiation forgenerating an image frame based on a plurality of independent exposureframes. The image frame may comprise information from a luminanceexposure frame, a blue chrominance exposure frame, and a red chrominanceexposure frame, and may further include information from one or more ofa hyperspectral exposure frame, a fluorescence exposure frame, and/or alaser mapping exposure frame. In FIG. 8, the pixel array 800 isillustrated with four different configurations over time, includingconfigurations for a first exposure frame 802, a second exposure frame804, a third exposure frame 806, and a fourth exposure frame 808. Thefirst exposure frame 802, the second exposure frame 804, the thirdexposure frame 806, and the fourth exposure frame 808 may be combined togenerate a single YCbCr image frame. One or more additional exposureframes may be combined with or overlaid on the YCbCr image frame,including for example, a hyperspectral exposure frame, a fluorescenceexposure frame, and/or a laser mapping or tool tracking exposure frame.In some instances, information from one or more of the hyperspectralexposure frame, the fluorescence exposure frame, and/or the lasermapping or tool tracking exposure frame is translated to numericalinformation, color overlays, or some other form, when combined with theRGB image frame.

When the pixel array 800 is configured for the first exposure frame 802,the pixels are operated to sense luminance (“Y”) information. The pixelconfiguration for the first exposure frame 802 includes only luminancepixels 810. When the pixel array 800 is configured for the secondexposure frame 804, the pixels are operated to sense blue chrominance(“Cb”) information. The pixel configuration for the second exposureframe 804 includes only blue chrominance pixels 812. When the pixelarray 800 is configured for the third exposure frame 806, the pixel areoperated to sense luminance information again. The pixel configurationfor the third exposure frame 806 includes only luminance pixels 810.When the pixel array 800 is configured for the fourth exposure frame808, the pixels are operated to sense red chrominance (“Cr”)information. The pixel configuration for the fourth exposure frame 808includes only red chrominance pixels 814.

FIG. 9 illustrates a pixel array 900 of an image sensor similar to thoseillustrated in FIGS. 8 and 10-14. The image sensor is configured forgenerating a YCbCr image frame based on a plurality of independentexposure frames captured by the pixel array 900. The pixel array 900 isillustrated in four different configurations over time, includingconfigurations for a first exposure frame 902, a second exposure frame904, a third exposure frame 906, and a fourth exposure frame 908. Theconfiguration of the pixels for the first exposure frame 902 includesluminance pixels 910. The configuration of the pixels for the secondexposure frame 904 includes blue chrominance pixels 912 and redchrominance pixels 914 arranged in a checkerboard pattern. Theconfiguration of the pixels for the third exposure frame 906 includesluminance pixels 910. The configuration of the pixels for the fourthexposure frame 908 includes blue chrominance pixels 912 and redchrominance pixels 914. In an embodiment, the pixel configurations forthe second exposure frame 904 and the fourth exposure frame 908 sensemodulated blue chrominance (“λY+Cb”) and modulated red chrominance(“δY+Cr”).

FIG. 10 illustrates a pixel array 1000 of an image sensor similar tothose illustrated in FIGS. 8-9 and 11-14. The image sensor is configuredfor generating a YCbCr image frame based on a plurality of independentexposure frames captured by the pixel array 1000. The pixel array 1000is illustrated with four different configurations over time, includingconfigurations for a first exposure frame 1002, a second exposure frame1004, a third exposure frame 1006, and a fourth exposure frame 1008. Thedata sensed by the pixel array 1000 for the multiple exposure frames1002, 1004, 1006, 1008 can be combined to generate a single YCbCr imageframe. The configuration of the pixels for the first exposure frame 1002includes luminance short exposure pixels (“Y_(S)”) 1016 and luminancelong exposure pixels (“Y_(L)”) 1018 arranged in a checkerboard pattern.The configuration of the pixels for the second exposure frame 1004includes blue chrominance pixels 1012 and red chrominance pixels 1014.The configuration of the pixels for the third exposure frame 1006includes luminance long exposure pixels 1018 and luminance shortexposure pixels 1016 arranged in a checkerboard pattern with an oppositeconfiguration with respect to the arrangement for the first exposureframe 1002. The configuration of the pixels for the fourth exposureframe 1008 includes blue chrominance pixels 1012 and red chrominancepixels 1014.

FIG. 11 illustrates a pixel array 1100 of an image sensor similar tothose illustrated in FIGS. 8-10 and 12-14. The image sensor isconfigured for generating a RGB image frame based on a plurality ofindependent exposure frames captured by the pixel array 1100. The pixelarray 1100 is illustrated with four different configurations over time,including configurations for a first exposure frame 1102, a secondexposure frame 1104, a third exposure frame 1106, and a fourth exposureframe 1108. The data sensed by the pixel array 1100 for the multipleexposure frames 1102, 1104, 1106, 1108 can be combined to generate asingle RGB image frame. The pixel configurations illustrated in FIG. 11alternate which subset of pixels are configured as long exposures andwhich are configured as short exposures on successive green exposureframes. This approach of using long and short exposure pixels increasesthe perceived resolution of the resultant image. It should beappreciated that the application of dual exposure sampling is notlimited to the green exposure frames. In various embodiments, the pixelsmay have independent dual exposure ratios applied for luminance, redchrominance, blue chrominance, red, green, or blue exposure frames.

The configuration of the pixels for the first exposure frame 1102includes green short exposure pixels (“G_(S)”) 1122 and green longexposure pixels (“G_(L)”) 1124 arranged in a checkerboard pattern. Theconfiguration of the pixels for the second exposure frame 1104 includesred pixels (“R”) 1120. The configuration of the pixels for the thirdexposure frame 1106 includes green long exposure pixels 1124 and greenshort exposure pixels 1122 arranged in a checkerboard pattern in anopposite configuration with respect to the checkerboard pattern of thefirst exposure frame 1102. The configuration of the pixels for thefourth exposure frame 1108 includes blue pixels (“B”) 1126.

FIG. 12 illustrates a pixel array 1200 of an image sensor similar tothose illustrated in FIGS. 8-11 and 13-14. The image sensor isconfigured for generating a YCbCr image frame based on a plurality ofindependent exposure frames captured by the pixel array 1200. The pixelarray 1200 is illustrated with four different configurations over time,including configurations for a first exposure frame 1202, a secondexposure frame 1204, a third exposure frame 1206, and a fourth exposureframe 1208. The data sensed by the pixel array 1200 for the multipleexposure frames 1202, 1204, 1206, 1208 can be combined to generate asingle YCbCr image frame. The pixel configuration for the first exposureframe 1202 includes luminance short exposure pixels 1216 and luminancelong exposure pixels 1218 arranged in a checkerboard pattern. The pixelconfiguration of the second exposure frame 1204 includes bluechrominance pixels 1212. The pixel configuration of the third exposureframe 1206 includes luminance long exposure pixels 1218 and luminanceshort exposure pixels 1216 arrange in a checkerboard pattern opposite tothe pattern of the first exposure frame 1202. The pixel configuration ofthe fourth exposure frame 1208 includes red chrominance pixels 1214.

FIG. 13 illustrates a pixel array 1300 of an image sensor similar tothose illustrated in FIGS. 8-12 and 14. The image sensor is configuredfor generating an RGB image frame based on a plurality of independentexposure frames captured by the pixel array 1300. The pixel array 1300is illustrated with four different configurations over time, includingconfigurations for a first exposure frame 1302, a second exposure frame1304, a third exposure frame 1306, and a fourth exposure frame 1308. Thedata sensed by the pixel array 1300 for the multiple exposure frames1302, 1304, 1306, 1308 can be combined to generate a single RGB imageframe. The pixel configuration for the first exposure frame 1302includes green short exposure pixels 1322 and green long exposure pixels1324 arranged in a checkerboard pattern. The pixel configuration for thesecond exposure frame 1304 includes red short exposure pixels (“R_(S)”)1328 and red long exposure pixels (“R_(L)”) 1330 arranged in acheckerboard pattern. The pixel configuration for the third exposureframe 1306 includes green short exposure pixels 1322 and green longexposure pixels 1324 arranged in a checkerboard pattern opposite to thepattern of the first exposure frame 1302. The pixel configuration forthe fourth exposure frame 1308 includes blue short exposure pixels(“B_(S)”) 1332 and blue long exposure pixels (“B_(L)”) 1334 arranged ina checkerboard pattern.

FIG. 14 illustrates a pixel array 1400 of an image sensor similar tothose illustrated in FIGS. 8-13. The image sensor is configured forgenerating a YCbCr image frame based on a plurality of independentexposure frames captured by the pixel array 1400. The pixel array 1400is illustrated with four different configurations over time, includingconfigurations for a first exposure frame 1402, a second exposure frame1404, a third exposure frame 1406, and a fourth exposure frame 1408. Thedata sensed by the pixel array 1400 for the multiple exposure frames1402, 1404, 1406, 1408 can be combined to generate a single YCbCr imageframe. The pixel configuration for the first exposure frame 1402includes luminance short exposure pixels 1416 and luminance longexposure pixels 1418 arranged in a checkerboard pattern. The pixelconfiguration for the second exposure frame 1404 includes bluechrominance short exposure pixels (“Cb_(S)”) 1436 and blue chrominancelong exposure pixels (“Cb_(L)”) 1438 arranged in a checkerboard pattern.The pixel configuration for the third exposure frame 1406 includesluminance short exposure pixels 1416 and luminance long exposure pixels1418 arranged in a checkerboard pattern opposite to the pattern of thefirst exposure frame 1402. The pixel configuration for the fourthexposure frame 1408 includes red chrominance short exposure pixels(“Cr_(S)”) 1440 and red chrominance long exposure pixels (Cr_(L)”) 1442arranged in a checkerboard pattern.

FIG. 15 illustrates a process flow 1500 for applying correctionalgorithms and frame reconstruction of a YCbCr image frame that furtherincludes fluorescence imaging data. In the case of the Y-Cb-Y-Cr pulsingscheme, the image data is already in the YCbCr color space followingcolor fusion. Therefore, in the process flow 1500 illustrated in FIG.15, the luminance and chrominance-based operations are performed upfrontbefore converting back to linear RGB color space to perform colorcorrections.

The process flow 1500 includes receiving image data from an image sensorat 1502. Sensor correction 1504 is performed on the sensor data. Thesuper resolution (SR) and color motion artifact correction (CMAC)algorithms are implemented at 1506. The SR and CMAC processes 1506 maybe performed within the camera image signal processor on raw, capturedsensor data. The SR and CMAC processes can be performed at 1506immediately after all digital sensor correction 1504 processes arecompleted. The SR and CMAC processes 1506 can be executed before thesensor data is fused into YCbCr space color images. Statistics can beexported at 1508 to determine the appropriate autoexposure for theimage.

A chrominance exposure frame 1510 a and a luminance exposure frame 1510b are constructed. In an embodiment, a fluorescence exposure frame 1510c is also constructed. The luminance exposure frame 1510 b isconstructed based on the Y frames in arrival order. The chrominanceexposure frames 1510 a are constructed based on the Cb and Cr frames inarrival order. The number of frames processed by the super resolutionalgorithm is an optional variable. The first-in-first-out depth of theluminance exposure frame 1510 b is normally odd and its size can bedetermined based on available processing, memory, memory-bandwidth,motion detection precision, or acceptable latency considerations. Thecolor motion artifact correction process can be performed with theminimum first-in-first-out depth of three frames for luminance and twoframes for blue chrominance and/or red chrominance. The super resolutionalgorithm may generate better resolution by the use of five luminanceframes.

The image data is processed to implement frame reconstruction at 1512and edge enhancement at 1514. The YCbCr image is converted to a linearRGB image at 1516. Statistics on the RGB image can be exported at 1518to determine appropriate white balance. The appropriate white balance isapplied at 1520 and entered into the color correction matrix at 1522.Scalars 1524 and gamma 1526 are determined and the video is exported at1528. The process flow 1500 can be implemented in the camera imagesignal processor in real-time while image data is captured and receivedfrom the sensor (see 1502).

During frame reconstruction 1512, there may be one full color imageframe in YCbCr space generated for each luminance exposure frame. Thedata captured in the luminance exposure frame may be combined with datafrom chrominance exposure frames captured before and after the luminanceexposure frame. Given this pulsing sequence, the position of the bluechrominance exposure frame with respect to the luminance exposure framemay be adjusted to occur before or after the luminance exposure framefor alternate luminance cases. The same is true for the red chrominanceexposure frame with respect to the luminance exposure frame. Therefore,the data from each captured blue chrominance or red chrominance exposureframe is used in two resultant full color images. The minimum framelatency may be provided by performing the frame reconstruction 1512process during the blue chrominance and red chrominance frame capture.

FIG. 16 is a schematic diagram of a process flow 1600 to be implementedby a controller and/or monochrome image signal processor (ISP) forgenerating a video stream having RGB images with fluorescence dataoverlaid thereon. In the process flow 1600, before applying gamma 1626to place the image data in the standard sRGB color space, additionaloperations including edge enhancement 1620 and other adjustments areperformed in an alternative color space such as the YCbCr or HSL colorspaces. In the example process flow 1600, the RGB image data isconverted to YCbCr to apply edge enhancement 1620 in the luminance planeand conduct filtering of the chrominance planes, and then the YCbCrimage is converted back to linear RGB color space.

The process flow 1600 results in images with increased dynamic range.The image signal processor (ISP) chain may be assembled for the purposeof generating sRGB image sequences from raw sensor data, yielded in thepresence of the G-R-G-B-Fluorescence light pulsing scheme. In theprocess flow 1600, the first stage is concerned with making correctionsto account for any non-idealities in the sensor technology for which itis most appropriate to work in the raw data domain. At the next stage,multiple frames (for example, a green frame 1612 a, a red-blue frame1612 b, and a fluorescence frame 1612 c) are buffered because each finalframe derives data from multiple raw frames. The frame reconstruction at1614 proceeds by sampling data from a current frame and buffered frames(see 1612 a, 1612 b, and/or 1612 c). The reconstruction process resultsin full color frames in linear RGB color space that include fluorescenceimage data.

In an embodiment, the process flow 1600 is applied to checkerboardreadings from a pixel array (see FIGS. 8-14). The checkerboard readingsmay be sensed in response to an R-G-B-G-Fluorescence orY-Cb-Y-Cr-Fluorescence pulsing scheme. The process flow 1600 includesreceiving data from an image sensor at 1602. Sensor correctioncalculations are performed at 1604. These sensor correction calculationscan be used to determine statistics at 1606 such as autoexposuresettings and wide dynamic range settings. The process flow 1600continues and wide dynamic range fusion is processed at 1608. Widedynamic range compression is processed at 1610. The wide dynamic rangecompression from 1610 can be fed to generate a green frame 1612 a, ared-blue frame 1612, and/or a fluorescence 1612 c. The process flow 1600continues and frame reconstruction is processed at 1614 and then colorcorrection is processed at 1616. The process flow 1600 continues and anRGB (red-green-blue) image is converted to a YCbCr image at 1618. Edgeenhancement is processed at 1620 and then the YCbCr image is convertedback to an RGB image at 1622. Scalars are processed at 1624 and gamma isprocessed at 1626. The video is then exported at 1628.

In an embodiment, the wide dynamic range fusion at 1608 is executedafter dark frame subtraction such that the mean black offset has beenadjusted to zero and the data may be signed. In an embodiment, it isdesirable to have the fixed pattern noise removed. The aim of the widedynamic range fusion 1608 process may be to combine the data from two ormore separate exposure frames into a single image frame prior to colorfusion. This may be accomplished by separating the two components of thecheckerboard pattern into two separate buffers and filling in the gapsby interpolation. There may be only one general kernel required becauseevery empty pixel sees the same local environment except for pixels nearthe edges of the image. A suitable convolution kernel for filling in thecheckerboard pattern by simple linear interpolation is:

$\begin{pmatrix}0 & \frac{1}{4} & 0 \\\frac{1}{4} & 0 & \frac{1}{4} \\0 & \frac{1}{4} & 0\end{pmatrix}\quad$

Following interpolation there may be two samples for each pixellocation. A gain may be applied to the short exposure sample, which maybe equal to the exposure-time ratio, T_(L)/T_(S). This requires theaddition of one extra bit for each factor-two of ratio. The fusionitself involves making a weighted sum of the two samples:

$x_{f} = {{\gamma \cdot ( \frac{T_{L}}{T_{S}} ) \cdot x_{S}} + {( {1 - \gamma} )x_{L}}}$

Where x_(S) and X_(L) may be the (signed) short and long exposuresignals respectively. The γ factor may be a function of the longexposure signal, x_(L), and may be set according to two thresholds, τ₁and τ₂. Below x_(L)=τ₁, γ=0.0, above γ=τ₂, γ=1.0. Between thethresholds, various functional forms may be employed and linear andcubic example behaviors of γ between τ₁ and τ₂, may be drawn. The valueof τ₂ may be set to the maximum possible value of x_(L), e.g., orsomething just below it. The purpose of the lower threshold, τ₁, may beto limit the influence of read noise from the short sample which has thegain factor T_(L)/T_(S) applied to it. It can be set to a conservativelyhigh constant, to accommodate the maximum ratio E, but it may be morebeneficial to have it vary linearly with T_(L)/T_(S);

$\tau_{1} = {( \frac{T_{L}}{T_{S}} ) \cdot \eta}$

The provision of two or more exposure frames within the same image framewithin a pulsed illumination endoscopy system may also be exploited forthe purpose of reducing the number of captured exposure frames per finalfull-color image from, from three to two. This suppresses possible colormotion artifacts that may be associated with an endoscopic imagingsystem.

An inherent property of the monochrome wide dynamic range array may bethat the pixels that have the long integration time may be integrate asuperset of the light seen by the short integration time pixels. Forregular wide dynamic operation in the luminance exposure frames, thatmay be desirable. For the chrominance exposure frames, it means that thepulsing may be controlled in conjunction with the exposure periods so asto e.g. provide λY+Cb from the start of the long exposure and switch toδY+Cr at the point that the short pixels may be turned on (both pixeltypes have their charges transferred at the same time). λ and δ may betwo tunable factors that may be used to bring all pulse energies topositive values.

During color correction 1616 in the ISP, the two flavors of pixel may beseparated into two buffers. The empty pixels are filled in using linearinterpolation. At this point, one buffer would contain a full image ofδY+Cr data and the other contains δY+CrαλY+Cb imaging data. The δY+Crbuffer would be subtracted from the second buffer to give λY+Cb. Thenthe appropriate proportion of luminance data from the luminance exposureframes would be subtracted out for each.

FIG. 17 is an example of color fusion hardware 1700. The color fusionhardware 1700 is deployed for generating an image frame according to apulsed lighting scheme as discussed herein. The color fusion process ismore straightforward than de-mosaic, which is necessitated by imagesensors with a color filter array, because there is no spatialinterpolation. The color fusion process performed by the color fusionhardware 1700 does not require buffering of exposure frames to have allnecessary information available for each pixel.

The memory writer 1702 receives a video data stream. In an embodiment,the video data stream includes Y-Cb-Y-Cr-Y-Cb-Y-Fluorescence exposureframes. In an alternative embodiment, the video data stream includesR-G-B-G-Fluorescence exposure frames. The video data stream may includeYCbCr or RGB exposure frames in combination with one or more ofhyperspectral exposure frames, fluorescence exposure frames, and/orlaser mapping or tool tracking exposure frames.

The memory writer 1702 writes the video data stream to memory 1704. Thevideo data stream may be parsed into, for example, a Cb+δY exposureframe, one or more luminance exposure frames, a Cr+λY exposure frame, ahyperspectral exposure frame, a fluorescence exposure frame, and/or alaser mapping exposure frame. Alternatively, the video data stream maybe parsed into, for example, a red exposure frame, one or more greenexposure frames, a blue exposure frame, a hyperspectral exposure frame,a fluorescence exposure frame, and/or a laser mapping exposure frame.The different exposure frames are read by the memory reader 1706 and aparallel RGB video data stream is generated at 1708. The pulse generatorand frame sync 1710 sends information to the memory writer 1704 and thememory reader 1706 to aid in fusing the multiple exposure frames.Information is output to the light source by the pulse generator andframe sync 1710.

FIG. 18 illustrates two corresponding histograms of black-correctedsignal for a region of an exposure frame. One of the histograms may beused, as mentioned earlier, to control the pulse energy level bycomparing a chosen percentile (P_(L)) of the distribution to a targetsignal level (S_(L), e.g. 50% of the digital dynamic range). Theexposure time of these type-1 pixels, T_(L), may be held at maximum. Thesubscript L here denotes the long exposure. The other histogram may beused to monitor the dynamic range of the scene by comparing anotherchosen percentile of the distribution, P_(S), where P_(S)>P_(L), andcomparing that with a different signal level, S_(S), where S_(S)>S_(L).The subscript S denotes the short exposure. S_(S) may be generally tunedclose to the top of the digital dynamic range. If P_(S)<S_(S), theexposure time for these type-2 pixels, T_(S), may be also held atmaximum. If P_(S)>S_(S), then T_(S) may be lowered until P_(S)=S_(S).There may be a predefined limit (E) as to how much the exposure timeratio may be allowed to increase to ensure that image qualitydegradation due to dynamic range enhancement outweighs the benefit ofenhancing the dynamic range. The values of P_(L), P_(S), S_(L), S_(S)and E may be tuned differently according to different applications andstored as factory presets. The exposure times T_(L) and T_(S) may berecorded for each exposure frame type, for use by the wide dynamic rangefusion process and by the color fusion ISP stage. In the case that thered, green, blue, and fluorescence pulse energies are modulated for thepurpose of white balance, the exposure times on the red and blue framesmay be governed by the green frames which may be exclusively used togather the wide dynamic range statistics.

In an implementation in which the imaging system is pulsing forluminance and chrominance illumination to generate a YCbCr image frame,the relative pulse energies may be held constant for a particular typeof exposure frame. The wide dynamic range control may be applied for theluminance frames as a baseline with the option of also applying widedynamic range independently on the chrominance frames. The histogramsmay be constructed on the raw black-corrected frame data as for theR-G-B-G scheme. Again, the exposure times for each frame type may berecorded for wide dynamic range fusion and for color fusion.

FIG. 19A shows the general situation of pipelining of data for theY-Cb-Y-Cr pattern which yields one full color image per two raw capturedimages. This is accomplished by using each chrominance sample twice. Inadditional embodiments, the data for the Y-Cb-Y-Cr pattern may furtherinclude data for hyperspectral, fluorescence, and/or laser mappingimaging.

FIG. 19B is an example of a 120 Hz frame capture rate providing a 60 Hzfinal video stream. The linear Y, Cb, and Cr components for each pixelmay be computed as follows:

     Y_(i) = 2^(m − 4) + (x_(i, n − 1) − K) ${\begin{Bmatrix}{{{Cb}_{i} = {2^{m - 1} + ( {x_{i,n} - K} ) - {\lambda \cdot ( {x_{i,{n - 1}} - K} )}}}\mspace{14mu}} \\{{Cr}_{i} = {2^{m - 1} + ( {x_{i,{n - 2}} - K} ) - {\delta \cdot ( {x_{i,{n - 1}} - K} )}}}\end{Bmatrix}\mspace{14mu}{when}\mspace{14mu} n} = {{‘{Cb}’}\mspace{14mu}{frame}}$$\mspace{76mu}{{\begin{Bmatrix}{{Cb}_{i} = {2^{m - 1} + ( {x_{i,{n - 2}} - K} ) - {\lambda \cdot ( {x_{i,{n - 1}} - K} )}}} \\{{{Cr}_{i} = {2^{m - 1} + ( {x_{i,n} - K} ) - {\delta \cdot ( {x_{i,{n - 1}} - K} )}}}\mspace{25mu}}\end{Bmatrix}\mspace{14mu}{when}\mspace{14mu} n} = {{‘{Cr}’}\mspace{14mu}{frame}}}$

Where x_(i,n) is the input data for pixel i in frame n, m is thepipeline bit-width of the ISP and K is the ISP black offset level at theinput to the color fusion block, (if applicable). Since chrominance issigned it is conventionally centered at 50% of the digital dynamic range(2^(m-1)).

If two exposures are used to provide both chrominance components in thesame frame as described earlier, the two flavors of pixel are separatedinto two buffers. The empty pixels are then filled in using, e.g.,linear interpolation. At this point, one buffer contains a full image ofδY+Cr data and the other; δY+Cr+λY+Cb. The δY+Cr buffer is subtractedfrom the second buffer to give λY+Cb. Then the appropriate proportion ofluminance data from the Y frames is subtracted out for each.

FIG. 20 is a schematic diagram of a pattern reconstruction process. Theexample pattern illustrated in FIG. 20 includes Red, Green, Blue, andFluorescence Excitation pulses of light that each last a duration of T1.In various embodiments, the pulses of light may be of the same durationor of differing durations. The Red, Green, Blue, and FluorescenceExcitation exposure frames are combined to generate an RGB image withfluorescence data overlaid thereon. A single image frame comprising ared exposure frame, a green exposure frame, a blue exposure frame, and afluorescence exposure frame requires a time period of 4*T1 to begenerated. The time durations shown in FIG. 20 are illustrative only andmay vary for different implementations. In other embodiments, differentpulsing schemes may be employed. For example, embodiments may be basedon the timing of each color component or frame (T1) and thereconstructed frame having a period twice that of the incoming colorframe (2×T1). Different frames within the sequence may have differentframe periods and the average capture rate could be any multiple of thefinal frame rate.

In an embodiment, the dynamic range of the system is increased byvarying the pixel sensitivities of pixels within the pixel array of theimage sensor. Some pixels may sense reflected electromagnetic radiationat a first sensitivity level, other pixels may sense reflectedelectromagnetic radiation at a second sensitivity level, and so forth.The different pixel sensitivities may be combined to increase thedynamic range provided by the pixel configuration of the image sensor.In an embodiment, adjacent pixels are set at different sensitivitiessuch that each cycle includes data produced by pixels that are more andless sensitive with respect to each other. The dynamic range isincreased when a plurality of sensitivities are recorded in a singlecycle of the pixel array. In an embodiment, wide dynamic range can beachieved by having multiple global TX, each TX firing only on adifferent set of pixels. For example, in global mode, a global TX1signal is firing a set 1 of pixels, a global TX2 signal is firing a set2 of pixel, a global TXn signal is firing a set n of pixels, and soforth.

FIGS. 21A-21C each illustrate a light source 2100 having a plurality ofemitters. The emitters include a first emitter 2102, a second emitter2104, and a third emitter 2106. Additional emitters may be included, asdiscussed further below. The emitters 2102, 2104, and 2106 may includeone or more laser emitters that emit light having different wavelengths.For example, the first emitter 2102 may emit a wavelength that isconsistent with a blue laser, the second emitter 2104 may emit awavelength that is consistent with a green laser, and the third emitter2106 may emit a wavelength that is consistent with a red laser. Forexample, the first emitter 2102 may include one or more blue lasers, thesecond emitter 2104 may include one or more green lasers, and the thirdemitter 2106 may include one or more red lasers. The emitters 2102,2104, 2106 emit laser beams toward a collection region 2108, which maybe the location of a waveguide, lens, or other optical component forcollecting and/or providing light to a waveguide, such as the jumperwaveguide 206 or lumen waveguide 210 of FIG. 2.

In an implementation, the emitters 2102, 2104, and 2106 emithyperspectral wavelengths of electromagnetic radiation. Certainhyperspectral wavelengths may pierce through tissue and enable a medicalpractitioner to “see through” tissues in the foreground to identifychemical processes, structures, compounds, biological processes, and soforth that are located behind the tissues in the foreground. Thehyperspectral wavelengths may be specifically selected to identify aspecific disease, tissue condition, biological process, chemicalprocess, type of tissue, and so forth that is known to have a certainspectral response.

In an implementation where a patient has been administered a reagent ordye to aid in the identification of certain tissues, structures,chemical reactions, biological processes, and so forth, the emitters2102, 2104, and 2106 may emit wavelength(s) for fluorescing the reagentsor dyes. Such wavelength(s) may be determined based on the reagents ordyes administered to the patient. In such an embodiment, the emittersmay need to be highly precise for emitting desired wavelength(s) tofluoresce or activate certain reagents or dyes.

In an implementation, the emitters 2102, 2104, and 2106 emit a lasermapping pattern for mapping a topology of a scene and/or for calculatingdimensions and distances between objects in the scene. In an embodiment,the endoscopic imaging system is used in conjunction with multiple toolssuch as scalpels, retractors, forceps, and so forth. In such anembodiment, each of the emitters 2102, 2104, and 2106 may emit a lasermapping pattern such that a laser mapping pattern is projected on toeach tool individually. In such an embodiment, the laser mapping datafor each of the tools can be analyzed to identify distances between thetools and other objects in the scene.

In the embodiment of FIG. 21B, the emitters 2102, 2104, 2106 eachdeliver laser light to the collection region 2108 at different angles.The variation in angle can lead to variations where electromagneticenergy is located in an output waveguide. For example, if the lightpasses immediately into a fiber bundle (glass or plastic) at thecollection region 2108, the varying angles may cause different amountsof light to enter different fibers. For example, the angle may result inintensity variations across the collection region 2108. Furthermore,light from the different emitters may not be homogenously mixed so somefibers may receive different amounts of light of different colors.Variation in the color or intensity of light in different fibers canlead to non-optimal illumination of a scene. For example, variations indelivered light or light intensities may result at the scene andcaptured images.

In one embodiment, an intervening optical element may be placed betweena fiber bundle and the emitters 2102, 2104, 2106 to mix the differentcolors (wavelengths) of light before entry into the fibers or otherwaveguide. Example intervening optical elements include a diffuser,mixing rod, one or more lenses, or other optical components that mix thelight so that a given fiber receive a same amount of each color(wavelength). For example, each fiber in the fiber bundle may have asame color. This mixing may lead to the same color in each fiber butmay, in some embodiments, still result in different total brightnessdelivered to different fibers. In one embodiment, the interveningoptical element may also spread out or even out the light over thecollection region so that each fiber carries the same total amount oflight (e.g., the light may be spread out in a top hat profile). Adiffuser or mixing rod may lead to loss of light.

Although the collection region 2108 is represented as a physicalcomponent in FIG. 21A, the collection region 2108 may simply be a regionwhere light from the emitters 2102, 2104, and 2106 is delivered. In somecases, the collection region 2108 may include an optical component suchas a diffuser, mixing rod, lens, or any other intervening opticalcomponent between the emitters 2102, 2104, 2106 and an output waveguide.

FIG. 21C illustrates an embodiment of a light source 2100 with emitters2102, 2104, 2106 that provide light to the collection region 2108 at thesame or substantially same angle. The light is provided at an anglesubstantially perpendicular to the collection region 2108. The lightsource 2100 includes a plurality of dichroic mirrors including a firstdichroic mirror 2110, a second dichroic mirror 2112, and a thirddichroic mirror 2114. The dichroic mirrors 2110, 2112, 2114 includemirrors that reflect a first wavelength of light but transmit (or aretransparent to) a second wavelength of light. For example, the thirddichroic mirror 2114 may reflect blue laser light provided by the thirdemitter, while being transparent to the red and green light provided bythe first emitter 2102 and the second emitter 2104, respectively. Thesecond dichroic mirror 2112 may be transparent to red light from thefirst emitter 2102, but reflective to green light from the secondemitter 2104. If other colors or wavelengths are included dichroicmirrors may be selected to reflect light corresponding to at least oneemitter and be transparent to other emitters. For example, the thirddichroic mirror 2114 reflect the light form the third emitter 2106 butis to emitters “behind” it, such as the first emitter 2102 and thesecond emitter 2104. In embodiments where tens or hundreds of emittersare present, each dichroic mirror may be reflective to a correspondingemitter and emitters in front of it while being transparent to emittersbehind it. This may allow for tens or hundreds of emitters to emitelectromagnetic energy to the collection region 2108 at a substantiallysame angle.

Because the dichroic mirrors allow other wavelengths to transmit or passthrough, each of the wavelengths may arrive at the collection region2108 from a same angle and/or with the same center or focal point.Providing light from the same angle and/or same focal/center point cansignificantly improve reception and color mixing at the collectionregion 2108. For example, a specific fiber may receive the differentcolors in the same proportions they were transmitted/reflected by theemitters 2102, 2104, 2106 and mirrors 2110, 2112, 2114. Light mixing maybe significantly improved at the collection region compared to theembodiment of FIG. 21B. In one embodiment, any optical componentsdiscussed herein may be used at the collection region 2108 to collectlight prior to providing it to a fiber or fiber bundle.

FIG. 21C illustrates an embodiment of a light source 2100 with emitters2102, 2104, 2106 that also provide light to the collection region 2108at the same or substantially same angle. However, the light incident onthe collection region 2108 is offset from being perpendicular. Angle2116 indicates the angle offset from perpendicular. In one embodiment,the laser emitters 2102, 2104, 2106 may have cross sectional intensityprofiles that are Gaussian. As discussed previously, improveddistribution of light energy between fibers may be accomplished bycreating a more flat or top-hat shaped intensity profile. In oneembodiment, as the angle 2116 is increased, the intensity across thecollection region 2108 approaches a top hat profile. For example, atop-hat profile may be approximated even with a non-flat output beam byincreasing the angle 2116 until the profile is sufficiently flat. Thetop hat profile may also be accomplished using one or more lenses,diffusers, mixing rods, or any other intervening optical componentbetween the emitters 2102, 2104, 2106 and an output waveguide, fiber, orfiber optic bundle.

FIG. 22 is a schematic diagram illustrating a single optical fiber 2202outputting via a diffuser 2204 at an output. In one embodiment, theoptical fiber 2202 has a diameter of 500 microns, a numerical apertureof 0.65, and emits a light cone 2206 of about 70 or 80 degrees without adiffuser 2204. With the diffuser 2204, the light cone 2206 may have anangle of about 110 or 120 degrees. The light cone 2206 may be a majorityof where all light goes and is evenly distributed. The diffuser 2204 mayallow for more even distribution of electromagnetic energy of a sceneobserved by an image sensor.

In one embodiment, the lumen waveguide 210 includes a single plastic orglass optical fiber of about 500 microns. The plastic fiber may be lowcost, but the width may allow the fiber to carry a sufficient amount oflight to a scene, with coupling, diffusion, or other losses. Forexample, smaller fibers may not be able to carry as much light or poweras a larger fiber. The lumen waveguide 210 may include a single or aplurality of optical fibers. The lumen waveguide 210 may receive lightdirectly from the light source or via a jumper waveguide. A diffuser maybe used to broaden the light output 206 for a desired field of view ofthe image sensor 214 or other optical components.

Although three emitters are shown in FIGS. 21A-21C, emitters numberingfrom one into the hundreds or more may be used in some embodiments. Theemitters may have different wavelengths or spectrums of light that theyemit, and which may be used to contiguously cover a desired portion ofthe electromagnetic spectrum (e.g., the visible spectrum as well asinfrared and ultraviolet spectrums). The emitters may be configured toemit visible light such as red light, green light, and blue light, andmay further be configured to emit hyperspectral emissions ofelectromagnetic radiation, fluorescence excitation wavelengths forfluorescing a reagent, and/or laser mapping patterns for calculatingparameters and distances between objects in a scene.

FIG. 23 illustrates a portion of the electromagnetic spectrum 2300divided into twenty different sub-spectrums. The number of sub-spectrumsis illustrative only. In at least one embodiment, the spectrum 2300 maybe divided into hundreds of sub-spectrums, each with a small waveband.The spectrum may extend from the infrared spectrum 2302, through thevisible spectrum 2304, and into the ultraviolet spectrum 2306. Thesub-spectrums each have a waveband 2308 that covers a portion of thespectrum 2300. Each waveband may be defined by an upper wavelength and alower wavelength.

Hyperspectral imaging includes imaging information from across theelectromagnetic spectrum 2300. A hyperspectral pulse of electromagneticradiation may include a plurality of sub-pulses spanning one or moreportions of the electromagnetic spectrum 2300 or the entirety of theelectromagnetic spectrum 2300. A hyperspectral pulse of electromagneticradiation may include a single partition of wavelengths ofelectromagnetic radiation. A resulting hyperspectral exposure frameincludes information sensed by the pixel array subsequent to ahyperspectral pulse of electromagnetic radiation. Therefore, ahyperspectral exposure frame may include data for any suitable partitionof the electromagnetic spectrum 2300 and may include multiple exposureframes for multiple partitions of the electromagnetic spectrum 2300. Inan embodiment, a hyperspectral exposure frame includes multiplehyperspectral exposure frames such that the combined hyperspectralexposure frame comprises data for the entirety of the electromagneticspectrum 2300.

In one embodiment, at least one emitter (such as a laser emitter) isincluded in a light source (such as the light sources 202, 2100) foreach sub-spectrum to provide complete and contiguous coverage of thewhole spectrum 2300. For example, a light source for providing coverageof the illustrated sub-spectrums may include at least 20 differentemitters, at least one for each sub-spectrum. In one embodiment, eachemitter covers a spectrum covering 40 nanometers. For example, oneemitter may emit light within a waveband from 500 nm to 540 nm whileanother emitter may emit light within a waveband from 540 nm to 580 nm.In another embodiment, emitters may cover other sizes of wavebands,depending on the types of emitters available or the imaging needs. Forexample, a plurality of emitters may include a first emitter that coversa waveband from 500 to 540 nm, a second emitter that covers a wavebandfrom 540 nm to 640 nm, and a third emitter that covers a waveband from640 nm to 650 nm. Each emitter may cover a different slice of theelectromagnetic spectrum ranging from far infrared, mid infrared, nearinfrared, visible light, near ultraviolet and/or extreme ultraviolet. Insome cases, a plurality of emitters of the same type or wavelength maybe included to provide sufficient output power for imaging. The numberof emitters needed for a specific waveband may depend on the sensitivityof a monochrome sensor to the waveband and/or the power outputcapability of emitters in that waveband.

The waveband widths and coverage provided by the emitters may beselected to provide any desired combination of spectrums. For example,contiguous coverage of a spectrum using very small waveband widths(e.g., 10 nm or less) may allow for highly selective hyperspectraland/or fluorescence imaging. The waveband widths may allow forselectively emitting the excitation wavelength(s) for one or moreparticular fluorescent reagents. Additionally, the waveband widths mayallow for selectively emitting certain partitions of hyperspectralelectromagnetic radiation for identifying specific structures, chemicalprocesses, tissues, biological processes, and so forth. Because thewavelengths come from emitters which can be selectively activated,extreme flexibility for fluorescing one or more specific fluorescentreagents during an examination can be achieved. Additionally, extremeflexibility for identifying one or more objects or processes by way ofhyperspectral imaging can be achieved. Thus, much more fluorescenceand/or hyperspectral information may be achieved in less time and withina single examination which would have required multiple examinations,delays because of the administration of dyes or stains, or the like.

FIG. 24 is a schematic diagram illustrating a timing diagram 2400 foremission and readout for generating an image. The solid line representsreadout (peaks 2402) and blanking periods (valleys) for capturing aseries of exposure frames 2404-2414. The series of exposure frames2404-2414 may include a repeating series of exposure frames which may beused for generating laser mapping, hyperspectral, and/or fluorescencedata that may be overlaid on an RGB video stream. In an embodiment, asingle image frame comprises information from multiple exposure frames,wherein one exposure frame includes red image data, another exposureframe includes green image data, and another exposure frame includesblue image data. Additionally, the single image frame may include one ormore of hyperspectral image data, fluorescence image data, and lasermapping data. The multiple exposure frames are combined to produce thesingle image frame. The single image frame is an RGB image withhyperspectral imaging data. The series of exposure frames include afirst exposure frame 2404, a second exposure frame 2406, a thirdexposure frame 2408, a fourth exposure frame 2410, a fifth exposureframe 2412, and an Nth exposure frame 2426.

Additionally, the hyperspectral image data, the fluorescence image data,and the laser mapping data can be used in combination to identifycritical tissues or structures and further to measure the dimensions ofthose critical tissues or structures. For example, the hyperspectralimage data may be provided to a corresponding system to identify certaincritical structures in a body such as a nerve, ureter, blood vessel,cancerous tissue, and so forth. The location and identification of thecritical structures may be received from the corresponding system andmay further be used to generate topology of the critical structuresusing the laser mapping data. For example, a corresponding systemdetermines the location of a cancerous tumor based on hyperspectralimaging data. Because the location of the cancerous tumor is known basedon the hyperspectral imaging data, the topology and distances of thecancerous tumor may then be calculated based on laser mapping data. Thisexample may also apply when a cancerous tumor or other structure isidentified based on fluorescence imaging data.

In one embodiment, each exposure frame is generated based on at leastone pulse of electromagnetic energy. The pulse of electromagnetic energyis reflected and detected by an image sensor and then read out in asubsequent readout (2402). Thus, each blanking period and readoutresults in an exposure frame for a specific spectrum of electromagneticenergy. For example, the first exposure frame 2404 may be generatedbased on a spectrum of a first one or more pulses 2416, a secondexposure frame 2406 may be generated based on a spectrum of a second oneor more pulses 2418, a third exposure frame 2408 may be generated basedon a spectrum of a third one or more pulses 2420, a fourth exposureframe 2410 may be generated based on a spectrum of a fourth one or morepulses 2422, a fifth exposure frame 2412 may be generated based on aspectrum of a fifth one or more pulses 2424, and an Nth exposure frame2426 may be generated based on a spectrum of an Nth one or more pulses2426.

The pulses 2416-2426 may include energy from a single emitter or from acombination of two or more emitters. For example, the spectrum includedin a single readout period or within the plurality of exposure frames2404-2414 may be selected for a desired examination or detection of aspecific tissue or condition. According to one embodiment, one or morepulses may include visible spectrum light for generating an RGB or blackand white image while one or more additional pulses are emitted to sensea spectral response to a hyperspectral wavelength of electromagneticradiation. For example, pulse 2416 may include red light, pulse 2418 mayinclude blue light, and pulse 2420 may include green light while theremaining pulses 2422-2426 may include wavelengths and spectrums fordetecting a specific tissue type, fluorescing a reagent, and/or mappingthe topology of the scene. As a further example, pulses for a singlereadout period include a spectrum generated from multiple differentemitters (e.g., different slices of the electromagnetic spectrum) thatcan be used to detect a specific tissue type. For example, if thecombination of wavelengths results in a pixel having a value exceedingor falling below a threshold, that pixel may be classified ascorresponding to a specific type of tissue. Each frame may be used tofurther narrow the type of tissue that is present at that pixel (e.g.,and each pixel in the image) to provide a very specific classificationof the tissue and/or a state of the tissue (diseased/healthy) based on aspectral response of the tissue and/or whether a fluorescent reagent ispresent at the tissue.

The plurality of frames 2404-2414 is shown having varying lengths inreadout periods and pulses having different lengths or intensities. Theblanking period, pulse length or intensity, or the like may be selectedbased on the sensitivity of a monochromatic sensor to the specificwavelength, the power output capability of the emitter(s), and/or thecarrying capacity of the waveguide.

In one embodiment, dual image sensors may be used to obtainthree-dimensional images or video feeds. A three-dimensional examinationmay allow for improved understanding of a three-dimensional structure ofthe examined region as well as a mapping of the different tissue ormaterial types within the region.

In an example implementation, a fluorescent reagent is provided to apatient, and the fluorescent reagent is configured to adhere tocancerous cells. The fluorescent reagent is known to fluoresce whenradiated with a specific partition of electromagnetic radiation. Therelaxation wavelength of the fluorescent reagent is also known. In theexample implementation, the patient is imaged with an endoscopic imagingsystem as discussed herein. The endoscopic imaging system pulsespartitions of red, green, and blue wavelengths of light to generate anRGB video stream of the interior of the patient's body. Additionally,the endoscopic imaging system pulses the excitation wavelength ofelectromagnetic radiation for the fluorescent reagent that wasadministered to the patient. In the example, the patient has cancerouscells and the fluorescent reagent has adhered to the cancerous cells.When the endoscopic imaging system pulses the excitation wavelength forthe fluorescent reagent, the fluorescent reagent will fluoresce and emita relaxation wavelength. If the cancerous cells are present in the scenebeing imaged by the endoscopic imaging system, then the fluorescentreagent will also be present in the scene and will emit its relaxationwavelength after fluorescing due to the emission of the excitationwavelength. The endoscopic imaging system senses the relaxationwavelength of the fluorescent reagent and thereby senses the presence ofthe fluorescent reagent in the scene. Because the fluorescent reagent isknown to adhere to cancerous cells, the presence of the fluorescentreagent further indicates the presence of cancerous cells within thescene. The endoscopic imaging system thereby identifies the location ofcancerous cells within the scene. The endoscopic imaging system mayfurther emit a laser mapping pulsing scheme for generating a topology ofthe scene and calculating dimensions for objects within the scene. Thelocation of the cancerous cells (as identified by the fluorescenceimaging data) may be combined with the topology and dimensionsinformation calculated based on the laser mapping data. Therefore, theprecise location, size, dimensions, and topology of the cancerous cellsmay be identified. This information may be provided to a medicalpractitioner to aid in excising the cancerous cells. Additionally, thisinformation may be provided to a robotic surgical system to enable thesurgical system to excise the cancerous cells.

In a further example implementation, a patient is imaged with anendoscopic imaging system to identify quantitative diagnosticinformation about the patient's tissue pathology. In the example, thepatient is suspected or known to suffer from a disease that can betracked with hyperspectral imaging to observe the progression of thedisease in the patient's tissue. The endoscopic imaging system pulsespartitions of red, green, and blue wavelengths of light to generate anRGB video stream of the interior of the patient's body. Additionally,the endoscopic imaging system pulses one or more hyperspectralwavelengths of light that permit the system to “see through” sometissues and generate imaging of the tissue that is affected by thedisease. The endoscopic imaging system senses the reflectedhyperspectral electromagnetic radiation to generate hyperspectralimaging data of the diseased tissue, and thereby identifies the locationof the diseased tissue within the patient's body. The endoscopic imagingsystem may further emit a laser mapping pulsing scheme for generating atopology of the scene and calculating dimensions of objects within thescene. The location of the diseased tissue (as identified by thehyperspectral imaging data) may be combined with the topology anddimensions information that is calculated with the laser mapping data.Therefore, the precise location, size, dimensions, and topology of thediseased tissue can be identified. This information may be provided to amedical practitioner to aid in excising, imaging, or studying thediseased tissue. Additionally, this information may be provided to arobotic surgical system to enable the surgical system to excise thediseased tissue.

FIG. 25 is a schematic diagram of an imaging system 2500 having a singlecut filter. The system 2500 includes an endoscope 2506 or other suitableimaging device having a light source 2508 for use in a light deficientenvironment. The endoscope 2506 includes an image sensor 2504 and afilter 2502 for filtering out unwanted wavelengths of light or otherelectromagnetic radiation before reaching the image sensor 2504. Thelight source 2508 transmits light that may illuminate the surface 2512in a light deficient environment such as a body cavity. The light 2510is reflected off the surface 2512 and passes through the filter 2502before hitting the image sensor 2504.

The filter 2502 may be used in an implementation where a fluorescentreagent or dye has been administered. In such an embodiment, the lightsource 2508 emits the excitation wavelength for fluorescing thefluorescent reagent or dye. Commonly, the relaxation wavelength emittedby the fluorescent reagent or dye will be of a different wavelength thanthe excitation wavelength. The filter 2502 may be selected to filter outthe excitation wavelength and permit only the relaxation wavelength topass through the filter and be sensed by the image sensor 2504.

In one embodiment, the filter 2502 is configured to filter out anexcitation wavelength of electromagnetic radiation that causes a reagentor dye to fluoresce such that only the expected relaxation wavelength ofthe fluoresced reagent or dye is permitted to pass through the filter2502 and reach the image sensor 2504. In an embodiment, the filter 2502filters out at least a fluorescent reagent excitation wavelength between770 nm and 790 nm. In an embodiment, the filter 2502 filters out atleast a fluorescent reagent excitation wavelength between 795 nm and 815nm. In an embodiment, the filter 2502 filters out at least a fluorescentreagent excitation wavelength between 770 nm and 790 nm and between 795nm and 815 nm. In these embodiments, the filter 2502 filters out theexcitation wavelength of the reagent and permits only the relaxationwavelength of the fluoresced reagent to be read by the image sensor2504. The image sensor 2504 may be a wavelength-agnostic image sensorand the filter 2502 may be configured to permit the image sensor 2504 toonly receive the relaxation wavelength of the fluoresced reagent and notreceive the emitted excitation wavelength for the reagent. The datadetermined by the image sensor 2504 may then indicate a presence of acritical body structure, tissue, biological process, or chemical processas determined by a location of the reagent or dye.

The filter 2502 may further be used in an implementation where afluorescent reagent or dye has not been administered. The filter 2502may be selected to permit wavelengths corresponding to a desiredspectral response to pass through and be read by the image sensor 2504.The image sensor 2504 may be a monochromatic image sensor such thatpixels of the captured image that exceed a threshold or fall below athreshold may be characterized as corresponding to a certain spectralresponse or fluorescence emission. The spectral response or fluorescenceemission, as determined by the pixels captured by the image sensor 2504,may indicate the presence of a certain body tissue or structure, acertain condition, a certain chemical process, and so forth.

FIG. 26 is a schematic diagram of an imaging system 2600 having multiplecut filters. The system 2600 includes an endoscope 2606 or othersuitable imaging device having a light source 2608 for use in a lightdeficient environment. The endoscope 2606 includes an image sensor 2604and two filters 2602 a, 2602 b. It should be appreciated that inalternative embodiments, the system 2600 may include any number offilters, and the number of filters and the type of filters may beselected for a certain purpose e.g., for gathering imaging informationof a particular body tissue, body condition, chemical process, and soforth. The filters 2602 a, 2602 b are configured for preventing unwantedwavelengths of light or other electromagnetic radiation from beingsensed by the image sensor 2604. The filters 2602 a, 2602 b may beconfigured to filter out unwanted wavelengths from white light or otherelectromagnetic radiation that may be emitted by the light source 2608.

Further to the disclosure with respect to FIG. 25, the filters 2602 a,2602 b may be used in an implementation where a fluorescent reagent ordye has been administered. The filters 2602 a, 2602 b may be configuredfor blocking an emitted excitation wavelength for the reagent or dye andpermitting the image sensor 2604 to only read the relaxation wavelengthof the reagent or dye. Further, the filters 2602 a, 2602 b may be usedin an implementation where a fluorescent reagent or dye has not beenadministered. In such an implementation, the filters 2602 a, 2602 b maybe selected to permit wavelengths corresponding to a desired spectralresponse to pass through and be read by the image sensor 2604.

The multiple filters 2602 a, 2602 b may each be configured for filteringout a different range of wavelengths of the electromagnetic spectrum.For example, one filter may be configured for filtering out wavelengthslonger than a desired wavelength range and the additional filter may beconfigured for filtering out wavelengths shorter than the desiredwavelength range. The combination of the two or more filters may resultin only a certain wavelength or band of wavelengths being read by theimage sensor 2604.

In an embodiment, the filters 2602 a, 2602 b are customized such thatelectromagnetic radiation between 513 nm and 545 nm contacts the imagesensor 2604. In an embodiment, the filters 2602 a, 2602 b are customizedsuch that electromagnetic radiation between 565 nm and 585 nm contactsthe image sensor 2604. In an embodiment, the filters 2602 a, 2602 b arecustomized such that electromagnetic radiation between 900 nm and 1000nm contacts the image sensor 2604. In an embodiment, the filters 2602 a,2602 b are customized such that electromagnetic radiation between 425 nmand 475 nm contacts the image sensor 2604. In an embodiment, the filters2602 a, 2602 b are customized such that electromagnetic radiationbetween 520 nm and 545 nm contacts the image sensor 2604. In anembodiment, the filters 2602 a, 2602 b are customized such thatelectromagnetic radiation between 625 nm and 645 nm contacts the imagesensor 2604. In an embodiment, the filters 2602 a, 2602 b are customizedsuch that electromagnetic radiation between 760 nm and 795 nm contactsthe image sensor 2604. In an embodiment, the filters 2602 a, 2602 b arecustomized such that electromagnetic radiation between 795 nm and 815 nmcontacts the image sensor 2604. In an embodiment, the filters 2602 a,2602 b are customized such that electromagnetic radiation between 370 nmand 420 nm contacts the image sensor 2604. In an embodiment, the filters2602 a, 2602 b are customized such that electromagnetic radiationbetween 600 nm and 670 nm contacts the image sensor 2604. In anembodiment, the filters 2602 a, 2602 b are configured for permittingonly a certain fluorescence relaxation emission to pass through thefilters 2602 a, 2602 b and contact the image sensor 2604. In anembodiment, a first filter blocks electromagnetic radiation having awavelength from about 770 nm to about 790 nm, and a second filter blockselectromagnetic radiation having a wavelength from about 795 nm to about815 nm.

In an embodiment, the system 2600 includes multiple image sensors 2604and may particularly include two image sensors for use in generating athree-dimensional image. The image sensor(s) 2604 may becolor/wavelength agnostic and configured for reading any wavelength ofelectromagnetic radiation that is reflected off the surface 2612. In anembodiment, the image sensors 2604 are each color dependent orwavelength dependent and configured for reading electromagneticradiation of a particular wavelength that is reflected off the surface2612 and back to the image sensors 2604. Alternatively, the image sensor2604 may include a single image sensor with a plurality of differentpixel sensors configured for reading different wavelengths or colors oflight, such as a Bayer filter color filter array. Alternatively, theimage sensor 2604 may include one or more color agnostic image sensorsthat may be configured for reading different wavelengths ofelectromagnetic radiation according to a pulsing schedule such as thoseillustrated in FIGS. 5-7E, for example.

FIGS. 27A and 27B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor 2700 having aplurality of pixel arrays for producing a three-dimensional image. Thethree-dimensional image sensor may be built on a plurality of substratesand may comprise the plurality of pixel arrays and other associatedcircuitry, wherein a plurality of pixel columns 2704 a forming the firstpixel array and a plurality of pixel columns 2704 b forming a secondpixel array are located on respective substrates 2702 a and 2702 b,respectively, and a plurality of circuit columns 2708 a and 2708 b arelocated on a separate substrate 2706. Also illustrated are theelectrical connections and communications between columns of pixels toassociated or corresponding column of circuitry.

The plurality of pixel arrays may sense information simultaneously andthe information from the plurality of pixel arrays may be combined togenerate a three-dimensional image. In an embodiment, an endoscopicimaging system includes two or more pixel arrays that can be deployed togenerate three-dimensional imaging. The endoscopic imaging system mayinclude an emitter for emitting pulses of electromagnetic radiationduring a blanking period of the pixel arrays. The pixel arrays may besynced such that the optical black pixels are read (i.e., the blankingperiod occurs) at the same time for the two or more pixel arrays. Theemitter may emit pulses of electromagnetic radiation for charging eachof the two or more pixel arrays. The two or more pixel arrays may readtheir respective charged pixels at the same time such that the readoutperiods for the two or more pixel arrays occur at the same time or atapproximately the same time. In an embodiment, the endoscopic imagingsystem includes multiple emitters that are each individual synced withone or more pixel arrays of a plurality of pixel arrays. Informationfrom a plurality of pixel arrays may be combined to generatethree-dimensional image frames and video streams.

FIGS. 28A and 28B illustrate a perspective view and a side view,respectively, of an implementation of a monolithic sensor 2800 having aplurality of pixel arrays for producing a three-dimensional image inaccordance with the teachings and principles of the disclosure. Such animplementation may be desirable for three-dimensional image capture,wherein the two-pixel arrays 2802 and 2804 may be offset during use. Inanother implementation, a first pixel array 2802 and a second pixelarray 2804 may be dedicated to receiving a predetermined range of wavelengths of electromagnetic radiation, wherein the first pixel array isdedicated to a different range of wavelength electromagnetic radiationthan the second pixel array.

FIGS. 29A and 29B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor 2900 built on aplurality of substrates. As illustrated, a plurality of pixel columns2904 forming the pixel array are located on the first substrate 2902 anda plurality of circuit columns 2908 are located on a second substrate2906. Also illustrated in the figure are the electrical connection andcommunication between one column of pixels to its associated orcorresponding column of circuitry. In one implementation, an imagesensor, which might otherwise be manufactured with its pixel array andsupporting circuitry on a single, monolithic substrate/chip, may havethe pixel array separated from all or a majority of the supportingcircuitry. The disclosure may use at least two substrates/chips, whichwill be stacked together using three-dimensional stacking technology.The first 2902 of the 2902 substrates/chips may be processed using animage CMOS process. The first substrate/chip 2902 may be comprisedeither of a pixel array exclusively or a pixel array surrounded bylimited circuitry. The second or subsequent substrate/chip 2906 may beprocessed using any process and does not have to be from an image CMOSprocess. The second substrate/chip 2906 may be, but is not limited to, ahighly dense digital process to integrate a variety and number offunctions in a very limited space or area on the substrate/chip, or amixed-mode or analog process to integrate for example precise analogfunctions, or a RF process to implement wireless capability, or MEMS(Micro-Electro-Mechanical Systems) to integrate MEMS devices. The imageCMOS substrate/chip 2902 may be stacked with the second or subsequentsubstrate/chip 2906 using any three-dimensional technique. The secondsubstrate/chip 2906 may support most, or a majority, of the circuitrythat would have otherwise been implemented in the first image CMOS chip2902 (if implemented on a monolithic substrate/chip) as peripheralcircuits and therefore have increased the overall system area whilekeeping the pixel array size constant and optimized to the fullestextent possible. The electrical connection between the twosubstrates/chips may be done through interconnects, which may be wirebonds, bump and/or TSV (Through Silicon Via).

It will be appreciated that the teachings and principles of thedisclosure may be used in a reusable device platform, a limited usedevice platform, a re-posable use device platform, or a singleuse/disposable device platform without departing from the scope of thedisclosure. It will be appreciated that in a re-usable device platforman end-user is responsible for cleaning and sterilization of the device.In a limited use device platform, the device can be used for somespecified amount of times before becoming inoperable. Typical new deviceis delivered sterile with additional uses requiring the end-user toclean and sterilize before additional uses. In a re-posable use deviceplatform, a third-party may reprocess the device (e.g., cleans, packagesand sterilizes) a single-use device for additional uses at a lower costthan a new unit. In a single use/disposable device platform a device isprovided sterile to the operating room and used only once before beingdisposed of.

EXAMPLES

The following examples pertain to preferred features of furtherembodiments:

Example 1 is a system. The system includes an emitter for emittingpulses of electromagnetic radiation and an image sensor comprising apixel array for sensing reflected electromagnetic radiation. The systemincludes a controller in electronic communication with the image sensorand the emitter configured to synchronize timing of the emitter and theimage sensor to generate a plurality of exposure frames. The system issuch that at least a portion of the pulses of electromagnetic radiationemitted by the emitter comprises one or more of: electromagneticradiation having a wavelength from about 770 nm to about 790 nm; orelectromagnetic radiation having a wavelength from about 795 nm to about815 nm.

Example 2 is a system as in Example 1, wherein the pixel array comprisesa plurality of pixels, and wherein a sensitivity of each of theplurality of pixels can be adjusted such that the pixel array compriseslong exposure pixel and short exposure pixels.

Example 3 is a system as in any of Examples 1-2, wherein at least aportion of the plurality of exposure frames comprises a luminanceexposure frame, a red chrominance exposure frame, and a blue chrominanceexposure frame, and wherein: the luminance exposure frame comprises longexposure pixel data and short exposure pixel data; and the redchrominance exposure frame comprises long exposure pixel data and shortexposure pixel data; and the blue chrominance exposure frame compriseslong exposure pixel data and short exposure pixel data.

Example 4 is a system as in any of Examples 1-3, wherein the emittermodulates the pulses of electromagnetic radiation to provide luminanceinformation according to color transformation coefficients that convertlight energy from red, green, and blue light energy space to luminance,blue chrominance, and red chrominance light energy space.

Example 5 is a system as in any of Examples 1-4, wherein the emittermodulates the pulses of electromagnetic radiation to provide chrominanceinformation according to color transformation coefficients that convertlight energy from red, green, and blue light energy space to luminance,blue chrominance, and red chrominance light energy space.

Example 6 is a system as in any of Examples 1-5, wherein the pulses ofelectromagnetic radiation are emitted according to a pulsing patterncomprising a luminance pulse, a blue chrominance pulse, a redchrominance pulse, and a fluorescence excitation pulse.

Example 7 is a system as in any of Examples 1-6, wherein the pulses ofelectromagnetic radiation are emitted according to a pulsing patterncomprising a luminance pulse, a combined blue chrominance and redchrominance pulse, and a fluorescence excitation pulse.

Example 8 is a system as in any of Examples 1-7, wherein the controlleris configured to generate image frames comprising data from a pluralityof exposure frames, wherein a single image frame comprises data from aluminance exposure frame, a chrominance exposure frame, and afluorescence exposure frame, wherein the fluorescence exposure frame issensed by the pixel array in response to an emission of electromagneticradiation of one or more of: the electromagnetic radiation having thewavelength from about 770 nm to about 790 nm; or the electromagneticradiation having the wavelength from about 795 nm to about 815 nm.

Example 9 is a system as in any of Examples 1-8, wherein the imagesensor is configured to generate a plurality of exposure frames, whereineach of the plurality of exposure frames corresponds to a pulse ofelectromagnetic radiation emitted by the emitter.

Example 10 is a system as in any of Examples 1-9, wherein the pixelarray of the image sensor senses reflected electromagnetic radiation togenerate the plurality of exposure frames during a readout period of thepixel array, wherein the readout period is a duration of time whenactive pixels in the pixel array are read.

Example 11 is a system as in any of Examples 1-10, wherein the pulses ofelectromagnetic radiation are emitted according to a pulsing patterncomprising a luminance pulse, a red chrominance pulse, a bluechrominance pulse, and a fluorescence excitation pulse, wherein theluminance pulse is represented in the pulsing pattern twice as often asthe red chrominance pulse, the blue chrominance pulse, or thefluorescence excitation pulse.

Example 12 is a system as in any of Examples 1-11, wherein at least aportion of the pulses of electromagnetic radiation emitted by theemitter is a fluorescence excitation wavelength for fluorescing areagent, wherein the fluorescence excitation wavelength comprises one ormore of: the electromagnetic radiation having the wavelength from about770 nm to about 790 nm; or the electromagnetic radiation having thewavelength from about 795 nm to about 815 nm.

Example 13 is a system as in any of Examples 1-12, wherein the emitteris configured to emit, during a pulse duration, a plurality ofsub-pulses of electromagnetic radiation having a sub-duration shorterthan the pulse duration.

Example 14 is a system as in any of Examples 1-13, wherein one or moreof the pulses of electromagnetic radiation emitted by the emittercomprise electromagnetic radiation emitted at two or more wavelengthssimultaneously as a single pulse or a single sub-pulse.

Example 15 is a system as in any of Examples 1-14, wherein at least aportion of the pulses of electromagnetic radiation emitted by theemitter is a fluorescence excitation emission that results in afluorescence exposure frame created by the image sensor, and wherein thecontroller is configured to provide the fluorescence exposure frame to acorresponding system that determines a location of a critical tissuestructure within a scene based on the fluorescence exposure frame.

Example 16 is a system as in any of Examples 1-15, wherein thefluorescence excitation emission comprises: the electromagneticradiation having the wavelength from about 770 nm to about 790 nm; orthe electromagnetic radiation having the wavelength from about 795 nm toabout 815 nm.

Example 17 is a system as in any of Examples 1-16, wherein thecontroller is further configured to: receive the location of thecritical tissue structure from the corresponding system; generate anoverlay frame comprising the location of the critical tissue structure;and combine the overlay frame with a color image frame depicting thescene to indicate the location of the critical tissue structure withinthe scene.

Example 18 is a system as in any of Examples 1-17, wherein the criticalstructure comprises one or more of a nerve, a ureter, a blood vessel, anartery, a blood flow, or a tumor.

Example 19 is a system as in any of Examples 1-18, wherein thecontroller is configured to synchronize timing of the pulses ofelectromagnetic radiation during a blanking period of the image sensor,wherein the blanking period corresponds to a time between a readout of alast row of active pixels in the pixel array and a beginning of a nextsubsequent readout of active pixels in the pixel array.

Example 20 is a system as in any of Examples 1-19, wherein two or morepulses of electromagnetic radiation emitted by the emitter result in twoor more instances of reflected electromagnetic radiation that are sensedby the pixel array to generate two or more exposure frames that arecombined to form an image frame.

Example 21 is a system as in any of Examples 1-20, wherein the imagesensor comprises a first image sensor and a second image sensor suchthat the image sensor can generate a three-dimensional image.

Example 22 is a system as in any of Examples 1-21, wherein the emitteris configured to emit a sequence of pulses of electromagnetic radiationrepeatedly sufficient for generating a video stream comprising aplurality of image frames, wherein each image frame in the video streamcomprises data from a plurality of exposure frames, and wherein each ofthe exposure frames corresponds to a pulse of electromagnetic radiation.

Example 23 is a system as in any of Examples 1-22, wherein the pulses ofelectromagnetic radiation are emitted in a pattern of varyingwavelengths of electromagnetic radiation, and wherein the emitterrepeats the pattern of varying wavelengths of electromagnetic radiation

Example 24 is a system as in any of Examples 1-23, wherein at least aportion of the pulses of electromagnetic radiation comprise a redwavelength, a green wavelength, a blue wavelength, and a fluorescenceexcitation wavelength such that reflected electromagnetic radiationsensed by the pixel array corresponding to each of the red wavelength,the green wavelength, the blue wavelength, and the fluorescenceexcitation wavelength can be processed to generate a Red-Green-Blue(RGB) image frame comprising an overlay of fluorescence imaging data,wherein the fluorescence excitation wavelength of electromagneticradiation comprises: the electromagnetic radiation having the wavelengthfrom about 770 nm to about 790 nm; or the electromagnetic radiationhaving the wavelength from about 795 nm to about 815 nm.

Example 25 is a system as in any of Examples 1-24, wherein at least aportion of the pulses of electromagnetic radiation comprise a luminanceemission, a red chrominance emission, a blue chrominance emission, and afluorescence excitation emission such that reflected electromagneticradiation sensed by the pixel array corresponding to each of theluminance emission, the red chrominance emission, the blue chrominanceemission, and the fluorescence excitation emission can be processed togenerate a YCbCr image frame comprising an overlay of fluorescenceimaging data, wherein the fluorescence excitation emission ofelectromagnetic radiation comprises: the electromagnetic radiationhaving the wavelength from about 770 nm to about 790 nm; or theelectromagnetic radiation having the wavelength from about 795 nm toabout 815 nm.

Example 26 is a system as in any of Examples 1-25, further comprising afilter that filters electromagnetic radiation having a wavelength fromabout 770 nm to about 790 nm.

Example 27 is a system as in any of Examples 1-26, further comprising afilter that filters electromagnetic radiation having a wavelength fromabout 795 nm to about 815 nm.

It will be appreciated that various features disclosed herein providesignificant advantages and advancements in the art. The following claimsare exemplary of some of those features.

In the foregoing Detailed Description of the Disclosure, variousfeatures of the disclosure are grouped together in a single embodimentfor the purpose of streamlining the disclosure. This method ofdisclosure is not to be interpreted as reflecting an intention that theclaimed disclosure requires more features than are expressly recited ineach claim. Rather, inventive aspects lie in less than all features of asingle foregoing disclosed embodiment.

It is to be understood that any features of the above-describedarrangements, examples, and embodiments may be combined in a singleembodiment comprising a combination of features taken from any of thedisclosed arrangements, examples, and embodiments.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the disclosure.Numerous modifications and alternative arrangements may be devised bythose skilled in the art without departing from the spirit and scope ofthe disclosure and the appended claims are intended to cover suchmodifications and arrangements.

Thus, while the disclosure has been shown in the drawings and describedabove with particularity and detail, it will be apparent to those ofordinary skill in the art that numerous modifications, including, butnot limited to, variations in size, materials, shape, form, function andmanner of operation, assembly and use may be made without departing fromthe principles and concepts set forth herein.

Further, where appropriate, functions described herein can be performedin one or more of: hardware, software, firmware, digital components, oranalog components. For example, one or more application specificintegrated circuits (ASICs) or field programmable gate arrays (FPGAs)can be programmed to carry out one or more of the systems and proceduresdescribed herein. Certain terms are used throughout the followingdescription and claims to refer to particular system components. As oneskilled in the art will appreciate, components may be referred to bydifferent names. This document does not intend to distinguish betweencomponents that differ in name, but not function.

The foregoing description has been presented for the purposes ofillustration and description. It is not intended to be exhaustive or tolimit the disclosure to the precise form disclosed. Many modificationsand variations are possible in light of the above teaching. Further, itshould be noted that any or all the aforementioned alternateimplementations may be used in any combination desired to formadditional hybrid implementations of the disclosure.

Further, although specific implementations of the disclosure have beendescribed and illustrated, the disclosure is not to be limited to thespecific forms or arrangements of parts so described and illustrated.The scope of the disclosure is to be defined by the claims appendedhereto, any future claims submitted here and in different applications,and their equivalents.

What is claimed is:
 1. A system for providing visualization in a lightdeficient environment, the system comprising: an endoscope; a waveguideattached to the endoscope; an emitter for emitting pulses ofelectromagnetic radiation, wherein the emitter comprises a plurality ofelectromagnetic sources, and wherein the plurality of electromagneticsources comprises a fluorescence source for emitting a fluorescenceexcitation pulse comprising electromagnetic radiation having awavelength from 770 nm to 790 nm; an image sensor comprising a pixelarray for sensing reflected electromagnetic radiation; a controller inelectronic communication with the image sensor and the emitterconfigured to synchronize timing of the emitter and the image sensor togenerate a plurality of exposure frames comprising a luminance exposureframe, a red chrominance exposure frame, a blue chrominance exposureframe, and a fluorescence exposure frame, and wherein the controller isfurther configured to control one or more of: a blanking period of theimage sensor or one or more of a pulse length or intensity of the pulsesof electromagnetic radiation emitted by the emitter based on a carryingcapacity of the waveguide; wherein the luminance exposure frame, the redchrominance exposure frame, the blue chrominance exposure frame, and thefluorescence exposure frame are used to form a color image frame withfluorescence image data.
 2. The system of claim 1, wherein the pixelarray comprises a plurality of pixels, and wherein a sensitivity of eachof the plurality of pixels can be controlled by the controller such thatthe pixel array comprises long exposure pixels and short exposurepixels.
 3. The system of claim 1, wherein: the luminance exposure framecomprises long exposure pixel data and short exposure pixel data; thered chrominance exposure frame comprises long exposure pixel data andshort exposure pixel data; and the blue chrominance exposure framecomprises long exposure pixel data and short exposure pixel data.
 4. Thesystem of claim 1, wherein the emitter modulates the pulses ofelectromagnetic radiation to provide luminance information according tocolor transformation coefficients that convert light energy from red,green, and blue light energy space to luminance, blue chrominance, andred chrominance light energy space.
 5. The system of claim 1, whereinthe emitter modulates the pulses of electromagnetic radiation to providechrominance information according to color transformation coefficientsthat convert light energy from red, green, and blue light energy spaceto luminance, blue chrominance, and red chrominance light energy space.6. The system of claim 1, wherein the pulses of electromagneticradiation are emitted according to a pulsing pattern comprising a greenpulse, a blue pulse, a red pulse, and the fluorescence excitation pulse.7. The system of claim 1, wherein the pulses of electromagneticradiation are emitted according to a pulsing pattern comprising a greenpulse, a combined red and blue pulse, and the fluorescence excitationpulse.
 8. The system of claim 1, wherein the controller is configured togenerate a video stream comprising a plurality of image frames, whereinat least a portion of the plurality of image frames comprises datacaptured by the pixel array in response to a pulse of greenelectromagnetic radiation, a pulse of blue electromagnetic radiation, apulse of red electromagnetic radiation, and the fluorescence excitationpulse comprising the electromagnetic radiation having the wavelengthfrom 770 nm to 790 nm.
 9. The system of claim 1, wherein the imagesensor is configured to generate each of the plurality of exposureframes in response to a pulse of electromagnetic radiation emitted bythe emitter.
 10. The system of claim 9, wherein the pixel array of theimage sensor senses reflected electromagnetic radiation to generate theplurality of exposure frames during a readout period of the pixel array,wherein the readout period is a duration of time when active pixels inthe pixel array are read.
 11. The system of claim 1, wherein the pulsesof electromagnetic radiation are emitted according to a pulsing patterncomprising a luminance pulse, a red chrominance pulse, a bluechrominance pulse, and a fluorescence excitation pulse, wherein theluminance pulse is represented in the pulsing pattern twice as often asthe red chrominance pulse, the blue chrominance pulse, or thefluorescence excitation pulse.
 12. The system of claim 1, wherein atleast a portion of the pulses of electromagnetic radiation emitted bythe emitter is the fluorescence excitation pulse for fluorescing areagent, wherein the fluorescence excitation pulse comprises theelectromagnetic radiation having the wavelength from 770 nm to 790 nm.13. The system of claim 1, wherein the emitter is configured to emit,during a pulse duration, a plurality of sub-pulses of electromagneticradiation having a sub-duration shorter than the pulse duration.
 14. Thesystem of claim 1, wherein one or more of the pulses of electromagneticradiation emitted by the emitter comprises electromagnetic radiationemitted at two or more wavelengths simultaneously as a single pulse or asingle sub-pulse.
 15. The system of claim 1, wherein at least a portionof the pulses of electromagnetic radiation emitted by the emitter is thefluorescence excitation pulse that results in the fluorescence exposureframe created by the image sensor, and wherein the controller isconfigured to provide the fluorescence exposure frame to a correspondingsystem that determines a location of a tissue structure within a scenebased on the fluorescence exposure frame.
 16. The system of claim 15,wherein the fluorescence excitation pulse comprises the electromagneticradiation having the wavelength from 770 nm to 790 nm.
 17. The system ofclaim 15, wherein the controller is further configured to: receive thelocation of the tissue structure from the corresponding system; generatean overlay frame comprising the location of the tissue structure; andcombine the overlay frame with the color image frame depicting the sceneto indicate the location of the tissue structure within the scene. 18.The system of claim 17, wherein the structure comprises one or more of anerve, a ureter, a blood vessel, an artery, a blood flow, or a tumor.19. The system of claim 1, wherein the controller is configured tosynchronize timing of the pulses of electromagnetic radiation during ablanking period of the image sensor, wherein the blanking periodcorresponds to a time between a readout of a last row of active pixelsin the pixel array and a beginning of a next subsequent readout ofactive pixels in the pixel array.
 20. The system of claim 1, wherein twoor more pulses of electromagnetic radiation emitted by the emitterresult in two or more instances of reflected electromagnetic radiationthat are sensed by the pixel array to generate two or more exposureframes that are combined to form an image frame.
 21. The system of claim1, wherein the image sensor comprises a first image sensor and a secondimage sensor such that the image sensor can generate a three-dimensionalimage.
 22. The system of claim 1, wherein the emitter is configured toemit a sequence of pulses of electromagnetic radiation repeatedlysufficient for generating a video stream comprising the plurality ofimage frames, wherein each image frame in the video stream comprisesdata from a plurality of exposure frames, and wherein each of theplurality of exposure frames corresponds to a pulse of electromagneticradiation.
 23. The system of claim 1, wherein the pulses ofelectromagnetic radiation are emitted in a pattern of varyingwavelengths of electromagnetic radiation, and wherein the emitterrepeats the pattern of varying wavelengths of electromagnetic radiation.24. The system of claim 1, wherein at least a portion of the pulses ofelectromagnetic radiation comprise a red wavelength, a green wavelength,a blue wavelength, and a fluorescence excitation wavelength such thatreflected electromagnetic radiation sensed by the pixel arraycorresponding to each of the red wavelength, the green wavelength, theblue wavelength, and the fluorescence excitation wavelength can beprocessed to generate a Red-Green-Blue (RGB) image frame comprising anoverlay of fluorescence imaging data, wherein the fluorescenceexcitation wavelength of electromagnetic radiation comprises theelectromagnetic radiation having the wavelength from 770 nm to 790 nm.25. The system of claim 1, wherein at least a portion of the pulses ofelectromagnetic radiation comprise a luminance emission, a redchrominance emission, a blue chrominance emission, and a fluorescenceexcitation emission such that reflected electromagnetic radiation sensedby the pixel array corresponding to each of the luminance emission, thered chrominance emission, the blue chrominance emission, and thefluorescence excitation emission can be processed to generate a YCbCrimage frame comprising an overlay of fluorescence imaging data, whereinthe fluorescence excitation emission of electromagnetic radiationcomprises the electromagnetic radiation having the wavelength from 770nm to 790 nm.
 26. The system of claim 1, further comprising a filterthat filters electromagnetic radiation having a wavelength from 770 nmto 790 nm.
 27. The system of claim 1, wherein the controller furthercontrols: one or more of the pulse length or intensity of the pulses ofelectromagnetic radiation emitted by the emitter based power outputcapability of the emitter; or the blanking period of the image sensorbased on the power output capability of the emitter.